ArticlePDF AvailableLiterature Review

The Urban Heat Island: Implications for Health in a Changing Environment

Authors:

Abstract and Figures

Purpose of review: The Urban Heat Island (UHI) is a well-studied phenomenon, whereby urban areas are generally warmer than surrounding suburban and rural areas. The most direct effect on health from the UHI is due to heat risk, which is exacerbated in urban areas, particularly during heat waves. However, there may be health benefits from warming during colder months. This review highlights recent attempts to quantitatively estimate the health impacts of the UHI and estimations of the health benefits of UHI mitigation measures. Recent findings: Climate change, increasing urbanisation and an ageing population in much of the world, is likely to increase the risks to health from the UHI, particularly from heat exposure. Studies have shown increased health risks in urban populations compared with rural or suburban populations in hot weather and a disproportionate impact on more vulnerable social groups. Estimations of the impacts of various mitigation techniques suggest that a range of measures could reduce health impacts from heat and bring other benefits to health and wellbeing. The impact of the UHI on heat-related health is significant, although often overlooked, particularly when considering future impacts associated with climate change. Multiple factors should be considered when designing mitigation measures in urban environments in order to maximise health benefits and avoid unintended negative effects.
This content is subject to copyright. Terms and conditions apply.
BUILT ENVIRONMENT AND HEALTH (MJ NIEUWENHUIJSEN AND AJ DE NAZELLE, SECTION EDITORS)
The Urban Heat Island: Implications for Health
in a Changing Environment
Clare Heaviside
1,2,3
&Helen Macintyre
1
&Sotiris Vardoulakis
2,3,4
#Springer International Publishing AG 2017
Abstract
Purpose of Review The Urban Heat Island (UHI) is a well-
studied phenomenon, whereby urban areas are generally
warmer than surrounding suburban and rural areas. The most
direct effect on health from the UHI is due to heat risk, which
is exacerbated in urban areas, particularly during heat waves.
However, there may be health benefits from warming during
colder months. This review highlights recent attempts to quan-
titatively estimate the health impacts of the UHI and estima-
tions of the health benefits of UHI mitigation measures.
Recent Findings Climate change, increasing urbanisation and
an ageing population in much of the world, is likely to in-
crease the risks to health from the UHI, particularly from heat
exposure. Studies have shown increased health risks in urban
populations compared with rural or suburban populations in
hot weather and a disproportionate impact on more vulnerable
social groups. Estimations ofthe impacts ofvarious mitigation
techniques suggest that a range of measures could reduce
health impacts from heat and bring other benefits to health
and wellbeing.
Summary The impact of the UHI on heat-related health is
significant, although often overlooked, particularly when con-
sidering future impacts associated with climate change.
Multiple factors should be considered when designing mitiga-
tion measures in urban environments in order to maximise
health benefits and avoid unintended negative effects.
Keywords Temp erature .Heat .Built environment .
Mitigation .Adaptation .Mortality .Cities
Introduction
People living in cities worldwide face a variety of risks to
health, due to pollution of the air, water and soil from industry
and traffic, from noise and from over-crowding and poor
housing [1]. This is of particular concern to the public health
community, as 2007 marked the tipping point whereby more
people lived in urban than rural areas, globally [2]. Increasing
urbanisation, climate change and ageing populations mean
that health risks for urban populations will continue to in-
crease in the future [3], particularly in the developing world
[4,5]. The Urban Heat Island (UHI) effect, which describes
the observation that temperatures in towns and cities are gen-
erally higher than in surrounding rural or suburban areas [6],
represents one mechanism by which the health of urban pop-
ulations can be compromised. The UHI effect can exacerbate
health impacts by affecting rainfall patterns [7], interacting
with and worsening air pollution [8], increasing flood risk
and decreasing water quality [9]. However, the most direct
impact of the UHI on human health is through exposure to
increased temperature, which can be particularly problematic
during heat waves.
There is a large body of research which associates exposure
to high or low temperatures to increased illness,
This article is part of the Topical Collection on Built Environment and
Health
*Clare Heaviside
clare.heaviside@phe.gov.uk
1
Environmental Change Department, Public Health England,
Harwell, Oxon OX11 0RQ, UK
2
School of Geography Earth and Environmental Sciences, University
of Birmingham, Birmingham B15 2TT, UK
3
Department of Social and Environmental Health Research, London
School of Hygiene and Tropical Medicine, 15-17 Tavistock Place,
London WC1H 9SH, UK
4
Institute of Occupational Medicine, Edinburgh EH14 4AP, UK
Curr Envir Health Rpt
DOI 10.1007/s40572-017-0150-3
hospitalisation and mortality, globally [1013]. Events such as
heat waves can lead to peaks in heat-related mortality over the
space of a few days, for example the European heat wave of
2003 was associated with thousands of excess deaths [14].
City populations are especially at risk due to the additional
higher temperature associated with the UHI effect during heat
waves, which can exacerbate health impacts from heat. For
example, Paris and other French cities were particularly affect-
ed by the 2003 heat wave [15,16].
We reviewed recent studies which characterised and
quantified health impacts relating to the UHI, primarily
throughexposuretoheat,andthosewhichassessedthe
potential impacts on health of UHI mitigation measures.
We did not review studies on measurements or the physics
of the UHI, subjects which are well covered elsewhere
[17,18]. Where possible we focused on studies which
provided quantitative estimates of the health impacts of
the UHI effect. Figure 1illustrates the main topics cov-
ered by this review.
Characterising and Measuring the Urban Heat
Island
The phenomenon of higher ambient temperatures in urban,
rather than rural or suburban environments, is largely ex-
plained by the differences between land surface materials
and building geometry in urban and rural areas, which influ-
ence the surface energy balance. In cities, urban materials such
as concrete and paving absorb energy from the sun during the
day, and slowly release this energy into the air as heat, mostly
at nighttime, which is when the temperature difference be-
tween urban and rural areas, and hence the UHI intensity, is
usually largest. The lack of moisture in urban areas and in-
creased anthropogenic heating also contribute to the UHI ef-
fect. The effect was first recorded in 1833 in London, using
observations [19]. Since then, the magnitude of the UHI effect
has been recognised and estimated in many cities around the
world.
The UHI effect can occur in any urbanised area, although it
is usually more noticeable in larger cities. UHI intensity,
usually defined and measured as the difference in temperature
between the centre of an urban area and the temperature of a
rural reference point outside of the city, scales approximately
with population size [20]. In extreme cases, usually at night-
time, temperatures can be up to 510 °C higher in the centre of
cities like New York, London, Manchester and Birmingham
than in the surrounding countryside; although on average, the
UHI intensity is usually around 2 to 4 °C [2124]. Even
though there is less incoming solar energy in winter than sum-
mer, the UHI effect can be large throughout the year. Most
UHI research focuses on summertime, since this is when most
of the potential harmful effects occur, and peak temperatures
are reached. Less research investigates the wintertime UHI
and potential benefits to health which may exist from winter
heating in urban areas. The conditions most favourable for a
large UHI effect are when skies are clear, due to the increased
solar heating in the daytime, and when winds are light so there
is a lack of atmospheric mixing and therefore dispersal of the
warm air. These conditions often coincide with heat waves,
where populations are particularly at risk from the effects of
heat.
Challenges When Assessing the Extent of the UHI Effect
Since the existence of the UHI has been acknowledged for so
long, methods to quantify its intensity have evolved over time.
These can be broadly classified by the use of (a) ground ob-
servations (either fixed or mobile), (b) satellite images or (c)
modelling using regional climate or meteorological models.
Traditionally, data from pairs of observational sites were
used to measure the UHI intensity, although the position and
local environment of the observational sites can vary by loca-
tion, which limits comparability between cities, and point
Fig. 1 Summary of topics covered in this review. Examples of relevant
publications on methods to assess health impacts ofthe Urban Heat Island
and on mitigation methods to reduce health impacts are indicated by
square brackets
Curr Envir Health Rpt
measurements provide little information on spatial variation in
temperature across a city. Additionally, temperature monitor-
ing stations have historically been sited outside of city centres
to reduce the potential for urban infrastructure influencing
ambient temperature measurements. Whilst this siting is use-
ful for analysis of long-term temperature trends without arti-
ficial influence, it can limit the availability of urban reference
temperature data points. Moving transects taken across a city
using vehicles may give more spatial information, and high-
density observational networks within cities have occasionally
been used [25], but these are difficult and costly to set up and
maintain. In recent years, satellite imagery has been used to
give an indication of the spatial variation in temperature across
a city, although the satellite images represent skinor surface
temperature, which is less relevant for human exposure than
air temperature at the surface, and images are limited to dis-
crete snapshots in time and only when there is no cloud cover.
These limitations mean that although the intensity of the
UHI can be estimated, there is a lack of high-quality informa-
tion on the variation of risk and population exposure to heat
across a city. This fact is highlighted by members of the public
health community, who outline the requirements for spatial
information on the UHI effect in order to identify areas, where
health impacts are likely to be larger, and in order to better
protect the public from harmful temperature effects [26].
Modelling studies using high-resolution regional weather
and climate models can provide an effective way to quantify
the UHI intensity, characterise spatial variations in tempera-
ture and, in theory, can be applied to any city in the world. In
order to be effective, relevant parameters representing urban
characteristics need to be included as inputs to the models, and
the unique nature of individual cities and local meteorology
should be observed [18]. The effects of urban parameters rel-
evant to the UHI, such as height, shape, three-dimensional
area and spatial distribution of buildings and other infrastruc-
ture can be determined using field and laboratory studies [27].
This information is then incorporated into building parameter
schemes, when running regional models, to improve surface
energy exchange in urban areas, e.g. [28]. In addition, by
varying model parameters, the range of effects of urban infra-
structure and the potential benefits of mitigation measures can
be investigated and quantified. Although modelled simula-
tions address some of the shortcomings of traditional measure-
ment techniques, they cannot replace the requirement for reli-
able observations which are essential for effective model
evaluation.
Health Implications of the UHI
Exposure to heat is associated with a range of adverse health
effects, ranging from exacerbation of minor existing condi-
tions to increased risk of hospitalisation and death [11]. Heat
stroke is not usually the sole cause of death; rather, heat is
often a contributory factor to deaths and morbidity from other
causes, such as respiratory illness [29]. This risk has been
shown to be significant at even moderately high temperatures
[12], although health effects are most severe during periods of
extremely high temperatures or heat waves. The enhancement
of temperatures due to the UHI effect therefore increases heat-
related mortality risk in urban areas, and this is likely to further
increase in future, due to climate change [30,31].
Temperatures during heat wave events generally reach a max-
imum during daytime hours, although high nighttime mini-
mum temperatures, which can keep indoor temperatures high,
are also likely to affect health, especially if a heat wave per-
sists over several days. For example, high nighttime tempera-
tures, a key characteristic of the UHI effect, were associated
with increased mortality during the 2003 heat wave in Paris
[32]. The populations most likely to be adversely affected by
heat are generally those in the older age groups and those with
existing health conditions.
Several studies have projected the potential impacts of heat
on mortality due to climate change [33,34], and some have
shown that although an increase in temperature may lead to
decreases in cold-related mortality in future, any benefits are
likely to be outweighed by the increase in heat-related deaths
due to the combined effects from projected increased mean
temperature and heat wave frequency and an ageing, growing
population [13,30]. Since there is less research on the poten-
tial health benefits of the UHI in preventing cold-related mor-
tality in winter months, interventions such as modifications to
building design to protect against the effects of heat should not
exacerbate the risks from cold, and vice versa [35]. Most stud-
ies based on climate projections do not explicitly include the
UHI effect due to the computational difficulty in resolving
features at the urban scale in global climate models, and this
may lead to underestimation of health impacts in urban areas
[36]. When urban schemes are included in models, the future
impact of the UHI is often discussed, but this is not always
related to a health burden [37]. In the following sections, we
focus on work which has sought to identify and quantify the
heat-related health impacts directly associated with the UHI.
Assessing Heat Risk in Urban Areas
Variations in land surface type mean that temperature varies
across a city resulting in similar variations in the potential for
population exposure to heat. Higher UHI intensities tend to
occur in centrally located parts of the city, where people are
often more likely to be socially disadvantaged. In turn, these
socio-economic factors may modify how harmful the UHI
effect can be and increase vulnerability to the UHI in urban
populations [1].There is evidence that vegetated and therefore
cooler neighbourhoods are home to more affluent populations
and that heat-related health risks are lower in these areas [38].
Curr Envir Health Rpt
In addition, poorer neighbourhoods often lack critical physical
and social resources to cope with extreme heat [39]. Studies in
the USA also suggest strong relationships between land cover,
neighbourhood social conditions and surface temperatures
[40]. In particular, surface temperature is statistically higher
in areas characterised by poverty, ethnic minority groups, lack
of education, elderly populations and increased crime due in
part to high population density and therefore abundance of
manmade surfaces in these areas [41].
Dwelling type and building characteristics play fundamen-
tal roles in determining health risks from heat, and are likely to
be linked to social factors. For example, air conditioning can
protect against heat-related impacts by reducing indoor tem-
perature, but is not always available to more vulnerable pop-
ulation groups, despite becoming more affordable. Air condi-
tioning can lead to increased energy consumption and green-
house gas emissions (when not powered by renewable energy
sources) and can exacerbate the UHI by dissipating heat out-
doors. Some evidence suggests that air conditioning needs to
be available in the whole house to be effective, and there is
also a risk that constant use can increase physiological depen-
dence upon it [42]. Building design to prevent overheating in
homes is a key factor determining the vulnerability of the
population and a research topic in itself [43].
Spatial Mapping to Identify Heat Risk
Mapping techniques to identify population risk from exposure
to heat across a city make use of highly spatially resolved
information from climate or meteorological modelling, satel-
lite imagery [44] or interpolated observations [45]tocharac-
terise variations in urban temperature. Other factors which
modify the effects of heat on health, such as age or socio-
economic distribution, can also be mapped at the same time.
Attempts have been made to combine maps of hazards, in-
cluding the UHI effect as well as environmental, demographic
or physical factors, to give indications of risk variability across
a city, in the form of heat risk models [4649]. In some cases,
this has resulted in creating an index of risk.
In the UK, the creation of a heat vulnerability index for the
city of London was based on nine proxy measures of heat risk,
selected following a literature search, and used principal com-
ponent analysis, weighted according to health impact [50].
The nine variables included information about housing,
socio-economic status, population density, access to heating
and air conditioning, occupant age and underlying health con-
dition. Results showed strong statistical evidence of clustering
of areas of high vulnerability, e.g. high population density in
central London and poor health statusand welfare dependency
in the east. Although satellite data and monitoring sites were
used to estimate the UHI intensity, there was a lack of consis-
tent highly spatially and temporally resolved temperature
information, and air pollution (often a significant risk factor
in urban areas) was not included as a risk factor [50].
Another London study highlighted the triple jeopardyof
age, UHI intensity and dwelling type (although not socio-
economic status) on heat risk [51]. High-resolution modelled
temperature for a single hot day was included in the study, and
the analysis was carried out using GIS techniques. Exposure
to daily mean maximum temperature was derived from out-
door temperature, UHI anomaly per dwelling (outdoor tem-
perature compared with the average outdoor temperature for
all dwellings) and indoor temperature. Results showed that
UHI intensity and particularly dwelling type were the main
factors contributing to heat mortality risk [51].
Quantification of the Health Burden Associated With
the UHI
Mapping studies go some way to identifying areas of heat
vulnerability, particularly when combined with demographic
and socio-economic data. Some mapping studies are linked
with recorded health data such as hospital admissions or mor-
tality figures, for example an analysis based on satellite data of
temperature for Philadelphia in the USA detected that the
spatial distribution of heat wave deaths in 1993 was co-
located with the urban poor as well as with higher UHI inten-
sity [52]. In Brisbane, hospital admissions data were analysed
using Bayesian modelling, and it was found there were signif-
icant increases in emergency, non-accidental hospitalizations
with increasing daily maximum temperature in summer for a
number of areas in the city, particularly those with high pop-
ulation density and low income [53]. An investigation of mor-
tality based on apparent temperature derived by spatial inter-
polation (using kriging) of sparse observation sites for
Massachusetts, USA, in urban and rural areas suggested that
demographic factors, such as ethnicity and age, may be more
important than level of urbanisation, at least for this particular
study area [54]. A US impact assessment for mortality and
energy use for cold and warm seasons [55] showed that the
impact of the UHI on heat-related deaths was estimated at an
increase of 1.1 deaths per million population, and the impact
of the UHI on cold-related deaths was a decrease of 4.0 deaths
per million. The author highlighted the importance of taking
the potential health benefits of the UHI into account as well as
costs. However, the results were derived simply by relating
information from death certificates on the underlying probable
cause of death (e.g. heat, cold) to urbanisation level in various
cities.
Epidemiological methods (cross sectional or longitudinal)
can be employed to investigate the risk of mortality depending
on the heat exposure experienced in different parts of a city,
often using satellite imagery. The analysis can be carried out
by (a) stratifying the data based on local temperature (or UHI
intensity), and calculating the temperature-mortality
Curr Envir Health Rpt
relationship separately for regions of different temperature,
e.g. [5658], or (b) by comparing results for urban and rural/
suburban areas [59]. Case-control epidemiological studies
may also be employed, based on urban and rural population
samples [32]. Analyses may include cold effects, as well as
heat, and morbidity as well as mortality, such as a study in the
Czech Republic which focused on cardiovascular outcomes
and found some evidence to suggest that the UHI was one
possible risk factor for heat stress, along with demographic
factors and exposure to air pollution [60]. A recent study for
London went further by seeking to investigate whether there
were differences in the susceptibility to heat and cold experi-
enced by populations in urban and rural regions using case-
crossover epidemiological analyses, and whether adaptation
to heat and cold could be detected [61]. The study used
modelled temperature for London at a resolution of 1 km
2
to
derive an UHI anomaly, defined here as the difference be-
tween local temperature and London mean temperature for
each day, and investigated different zones around London.
There was some evidence for acclimatisation or adaptation
to heat in London, although this was not clear for cold effects
[61].
Health impact assessment methods can be employed to
estimate the health burden of the UHI in terms of the heat-
related mortality associated with the excess temperature due to
the UHI effect. Such studies use epidemiologically derived
relationships between temperature and mortality, along with
highly spatially resolved modelled temperature exposure data
and baseline health data to estimate the impact of the UHI
intensity on heat-related mortality. For example, the spatial
study [51] described above went on to combine modelled
urban temperatures at 1 km
2
resolutionandanexisting
temperature-mortality relationship to determine how heat-
related mortality was affected by various factors in London.
The modelled temperature in this case was used to derive an
UHI anomaly based on building location compared with the
London average, rather than compared with a rural or subur-
ban reference, and the impact analysis was based on indoor air
temperatures, which are heavily modified by dwelling charac-
teristics [51].
Another London-based analysis included projected temper-
atures and population to calculate the effects ofclimate change
on heat mortality [62]. They used a Climate Projections
Weather Generator (UCKP09) for future decades, which sim-
ulates temperature projections for each 5 km
2
grid cell, and
included downscaled information on the UHI based on de-
rived relationships between land use and anthropogenic heat
flux [62]. A sensitivity analysis for adaptation to the order of 1
or 2 °C is included to demonstrate that heat-related mortality
may be reduced by 32 to 69% in the future, although this 1
2 °C degree of adaptation is not based on empirical evidence
of the scale of adaptation we might expect in future, and which
is uncertain [63].
To directly estimate the impact on health that can be attrib-
uted to the UHI, modelling techniques can be employed to
estimate the impact of land use on temperature, and hence
on heat mortality. In a recent modelling experiment, tempera-
tures were simulated by regional climate models at high reso-
lution, with and without urban surfaces in the West Midlands,
a region of the UK, for the 2003 heat wave, and for projected
temperatures in future decades [36]. A health impact assess-
ment was carried out for the two modelled simulations, with
and without urban land use, and the mortality results were
compared in order to quantify the role of urban surfaces in
relation to heat mortality. The experiment showed that around
half of the heat-related mortality during the heat wave period
in August 2003 in the West Midlands could be attributed to the
UHI effect, i.e. the excess heat mortality as a result of the
excess temperature due to the UHI [36]. Projections for the
future suggested that a similar heat wave event in 2080, under
a medium climate change emission scenario, could lead to a
threefold increase in heat-related mortality [36]. Another
study, this time based in the USA analysed the relationship
between temperature and mortality and included climate and
urbanisation projections for the future to calculate mortality
[64]. They found that increases in minimum and mean tem-
peratures were responsible for projected increases in annual
heat-related mortality of around 50% and up to 300% by the
2050s.These types of study make a case for consideration of
the enhancement of temperature from urban surfaces when
calculating health impacts under climate change conditions
using global climate models; otherwise, the potential effects
of the UHI on health will not be fully captured.
Mitigation Techniques for Reducing the Harmful
Effects of the UHI
There are two broad types of mitigation technique for reduc-
ing the UHI effect at the city scale:those whichaim to increase
solar reflectivity, using coolor reflective materials for build-
ings and surfaces, and those which aim to increase evapotrans-
piration through increased greening and water availability.
The harmful effects of excess heat associated with the UHI
may also be mitigated through behavioural change, improved
building design and reduced anthropogenic heat emissions in
urban areas.The adoptionof heat-health warning systems [65]
tailored to urban environments could be considered to be an
alternative mitigation measure [66]. Detailed reviews on the
various techniques employed to counteract the UHI effect in
terms of temperature reduction are covered elsewhere, e.g.
[67]. Here we consider mitigation measures in the context of
reduction of negative health impacts.
Reflective or cool roofs are characterised by their ability to
reflect solar energy, and, as such, can be used as a counter-
measure to reduce the impacts of the UHI effect [68,69]. The
Curr Envir Health Rpt
heat-related health benefits from the implementation of cool or
reflective roofs and pavements can therefore be considered to
be a direct effect resulting from a reduction in local tempera-
ture. The health benefits relating to increasing urban green
space or blue space (water), however, are more complex. It
is widely understood that urban greening can have a positive
effect on reducing the UHI effect [7072], but there may be
additional benefits of urban greening on health, through re-
duced temperature exposure, increased access to green space
(which may improve mental health and wellbeing), reductions
to air pollution and more [73]. In Lisbon, Portugal, proximity
to urban green and blue spaces was associated with decreased
mortality for elderly populations, after adjusting for confound-
ing factors, and in the case of water bodies, the health benefit
was still seen several kilometres away [74]. The authors ac-
knowledge that it was not possible to determine whether the
health benefits resulted from reduced temperature, improved
health status of populations near green and blue spaces or from
reduced stress. Similarly, a protective effect of green space on
mortality was found for areas with low socio-economic status
in Spain [75]. Literature reviews of the evidence for the health
benefits of urban green spaces conclude that although they are
generally found to be good for health, a causal relationship is
difficult to determine, given the complexity of the relation-
ships involved [76,77].
Green roofs are another method employed to mitigate UHI
intensity by introducing vegetation at roof level to increase
evapotranspiration. Vertical green wallscan also carry out
a similar function [78]. Unlike cool roofs, which are fairly
simple in their function of reflecting solar radiation, a number
of factors determine the effectiveness of green roofs in reduc-
ing UHI intensity. The cooling potential depends on local
climate, vegetation type, density, soil depth, irrigation and
maintenance, and in some cases, the reflectivity (albedo) of
green roofs may be lower than the reflectivity of the original
roofing material [79]. A further consideration is that since the
vegetation is at roof height, there is less benefit from the
greening to be felt at ground level. There are, however, likely
to be benefits of green roofs in terms of CO
2
uptake, air pol-
lution reduction, run-off reduction, biodiversity and in insu-
lating effects in winter [80,81].
Cool roofs are considered to be a more practical, cheaper
method of UHI mitigation than green roofs [82], although
green roofs and walls can make useful contributions to a range
of health improvements. The reported health benefits of well-
designed and maintained urban green spaces make them de-
sirable to include within urban environments, whilst taking
care to minimise any potential risks, for example from urban
vectors or pollen emissions [83]. It is worth noting that al-
though many studies investigate the potential effects of
greeningof cities, in practice, trees and green spaces are
more often lost to urban development and infrastructure.
Whilst it is useful to quantify the benefits of adding green
space, particularly when developing and urbanising existing
green areas, we should be realistic as to the practicality of
greening large areas of our existing cities.
In this review, we do not cover the topics of building design
and modification, for example the use of external shutters or
shading to mitigate the UHI and minimise overheating im-
pacts. It is worth noting that one mitigation measure for
minimising heat-related health impacts from the UHI which
does not require physical changes to infrastructure is the im-
plementation of heat-health warning systems such as heat
wave plans [65,84,85]. These plans should acknowledge that
heat effects are likely to be more pronounced in city centres,
where residents may experience adverse health effects due to
higher temperatures compared to surrounding rural areas.
Assessing the Health Benefits of UHI Mitigation
Modelling can be used to estimate potential health benefits
and costs relating to various mitigation measures through im-
pact assessment methods. For example, benefits from reduc-
tions in UHI intensity from reflective roofs may have unin-
tended consequences in terms of increasing concentrations of
some air pollutants, depending on the method employed, for
example changes in solar reflectivity can affect local chemical
production of ozone [69]. This highlights the need for inte-
grated modelling techniques and the use of multi-criteria de-
cision analysis when considering planning and policy imple-
mentation [86]. Spatial mapping techniques may provide in-
formation on any disparity of the effectiveness of strategies
based on various demographic and socio-economic factors
[87] and make the case for actions at the local level [88].
Recent work investigating heat-related health risks and the
potential for countermeasures to the UHI highlights the im-
portance of considering the indoor environment, when many
studies focus only on reduction of outdoor temperatures [89].
Results showed that reductions in outdoor temperature do not
always reduce the indoor heat risk and that for the indoor
environment, trees, green and cool (reflective) roofs and pav-
ing may have some benefits to health, but passive cooling and
air conditioning should also be considered for risk reduction
[89]. However, the hazard reduction potential is presented
qualitatively and data on the effectiveness of air conditioning
is sparse. Air conditioning may be beneficial to health in hot
weather, but it is problematic in terms of increasing unwanted
anthropogenic heating, energy consumption and emissions of
greenhouse gases. Reliance on air conditioning may become
challenging in the event of power outages, so passive mea-
sures to provide cooling in buildings are more desirable [42].
Quantitative methods have been employed to estimate the
future health effects of climate change alongside various mit-
igation measures, e.g. using spatial and risk assessment
methods quantitatively, to show that increasing vegetation
(tree coverage) could reduce heat stress effects through
Curr Envir Health Rpt
increased evapotranspiration in a US study [90]. The use of
trees has multiple co-benefits, such as social improvements
and protection from urban flooding, although a potential
downside is increased water demand and energy demand for
maintenance. Street trees can be considered to provide eco-
system servicesin terms of improved human health, and are
linked with wider co-benefits, as well as potential unintended
negative effects [83]. To maximise the benefits, care needs to
be given to design of the tree canopy, choice of species and the
need for maintenance.
Parameters in urban climate models can be adapted to sim-
ulate the effects on changes in local temperature from, for
example a change in reflectivity (albedo) of roofs [48], and
to calculate the potential number of deaths avoidedby var-
ious UHI mitigation methods. This technique was carried out
for New York to investigate the impacts of mitigation on the
UHI, energy use and atmospheric chemistry, and applied to a
hybrid model to investigate the potential benefits to health
[91]. The author suggests that in mid-latitudes, cool roofs do
not modify the winter UHI, and will therefore not lead to an
increase in cold-related mortality. An increased rooftop albedo
from 0.32 to 0.90 related to around 45 avoided heat-related
deaths per year in New York City.
A study based on US metropolitan areas estimated changes
in heat-related deaths up to 2050 resulting from changes in
vegetative cover and surface albedo, and found that combina-
tions of these measures could offset 4099% of the projected
increases due to climate change [92]. In a related study, four
different mitigation strategies were assessed as to their impact
on emergency service calls, with increased albedo being
highlighted as the most effective strategy in a model for
Arizona, USA [93]. In Melbourne, Australia, urban climate
modelling of ten urban vegetation schemes for current and
future climates was carried out to investigate the effect on
heat-related mortality. The study found decreased temperature
and related mortality with greening simulations; however, the
scale of greening in the central business district would have to
be reasonably substantial to achieve the desired health benefits
(reductions in mortality from 5 to 28% with an increase in
vegetation cover from 15 to 33%) [94].
Impact modelling, incorporating environmental, social and
demographic information, is essential as a tool for assessing
potential benefits of UHI interventions, but it is difficult to
validate the estimated impacts against observed impacts. A
system-based approach may be necessary to examine the full
range of impacts, benefits and costs [73]. A US case study
highlights the complexity of designing effective UHI mitiga-
tion policies, and provides recommendations on how policy
makers can optimise performance by clearly identifying an
endpoint and integrating scientific and location specific infor-
mation to overcome existing limitations [95]. Specific end-
points should be determined from the start (e.g. reduce heat-
related mortality) rather than be related to the intervention
(e.g. plant a certain number of trees) so that success can be
driven by a better understanding of the desired goal.
Conclusions
There is a wealth of existing research on the UHI phenome-
non, the impact of heat and climate change on health and the
use of building and urban planning to make our cities more
healthy and sustainable. This review has only focused on re-
cent literature which aims to quantitatively assess the heat-
related health impacts of the UHI effect, and how these im-
pacts may be avoided through various mitigation techniques.
We identified numerous spatial mapping studies which are
intended to help local authorities and public health practi-
tioners to identify vulnerable populations. However, in order
for this type of work to prove useful, close collaboration be-
tween researchers and policy-makers is essential [96].
Quantification of the UHI impact on health is necessary to
increase the understanding of policy makers of the present
and future risks to health of urban populations, particularly
in the context of climate change. Care should be taken to
consider multiple exposures in urban environments, which
may compound or modify the direct impacts of heat on health;
air pollution is a problem in many cities, and should be con-
sidered alongside the UHI effect as a hazard to urban health.
The work presented here shows that when projecting future
heat impacts, omitting the additional temperature increase as-
sociated with the UHInot often characterised in global
modelsmay lead to underestimations of health effects. We
have mainly focused on heat-related health impacts, but more
research on the winter-time UHI is required to ensure that
implementation of planning policy minimises risks in both
cold and warm seasons.
We reviewed the most commonly implemented mitigation
measures and studies which aimed to quantify the potential
health benefits of a range of interventions. This has highlight-
ed again the multiple factors at play, and the need to consider
unintended consequences and benefits to health of policies
designed to protect against the UHI. The assessment of im-
pacts of mitigation measures should also highlight risks, so as
to prevent unintended negative effects, particularly in rapidly
urbanising countries.
The current quantity of research on the link between envi-
ronment and health and wellbeing can provide fundamental
evidence of the health benefits we may experience through
careful planning and design of our urban spaces. The public
health and environmental community should continue to work
together to promote measures which provide co-benefits in
terms of health, the environment and the economy, for exam-
ple through cleaner energy, active travel or centralised trans-
port initiatives, all of which are particularly relevant to urban
environments. With a growing, ageing and more urbanised
Curr Envir Health Rpt
population expected in most parts of the world, the develop-
ment of healthy, sustainable cities, based on sound scientific
evidence, should be considered a priority for improved public
health and wellbeing.
Acknowledgements The research was partly funded by the National
Institute for Health Research Health Protection Research Unit (NIHR
HPRU) in Environmental Change and Health at the London School of
Hygiene and Tropical Medicine in partnership with Public Health
England (PHE) and in collaboration with the University of Exeter,
University College London and the Met Office. The views expressed
are those of the author(s) and not necessarily those of the NHS, the
NIHR, the Department of Health or Public Health England.
Compliance with Ethical Standards
Conflict of Interest Clare Heaviside, Helen Macintyre and Sotiris
Vardoulakis declare that they have no conflict of interest.
Human and Animal Rights and Informed Consent This article does
not contain any studies with human or animal subjects performed by any
of the authors.
References
Papers of particular interest, published recently, have been
highlighted as:
Of importance
1. Vardoulakis S, Dear K, Wilkinson P. Challenges and opportunities
for urban environmental health and sustainability: the HEALTHY-
POLIS initiative. Environ Health. 2016;15(Suppl 1):S30.
2. UN. World urbanization prospects, the 2009 revision. New York:
United Nations; 2009.
3. Patz JA, Campbell-Lendrum D, Holloway T, Foley JA. Impact of
regional climate change on human health. Nature. 2005;438:3107.
4. McMichael A, Wilcox B. Climate change, human health, and inte-
grative research: a transformative imperative. EcoHealth. Springer
New York. 2009;6:1634.
5. Campbell-Lendrum D, Corvalán C. Climate change and
developing-country cities: implications for environmental health
and equity. J Urban Heal. 2007;84:i10917.
6. Oke TR. The energetic basis of the urban heat island (Symons
Memorial Lecture, 20 May 1980). Q Journal, R Meteorol Soc.
1982;108:124.
7. Collier CG. The impact of urban areas on weather. Q J R Meteorol
Soc. 2006;132:125.
8. Xu LY, Yin H, Xie XD. Health risk assessment of inhalable partic-
ulate matter in Beijing based on the thermal environment. Int J
Environ Res Public Health. MDPI AG. 2014;11:1236888.
9. Hester ET, Bauman KS. Stream and retention pond thermal re-
sponse to heated summer runoff from urban impervious surfaces.
J Am Water Resour Assoc. 2013;49:32842.
10. Baccini M, Biggeri A, Accetta G, Kosatsky T, Katsouyanni K,
Analitis A, et al. Heat effects on mortality in 15 European cities.
Epidemiology. 2008;19:7119.
11. Basu R. High ambient temperature and mortality: a review of epi-
demiologic studies from 2001 to 2008. Environ. Heal. A Glob.
Access Sci. Source. 2009;8.
12. Gasparrini A, Guo Y, Hashizume M, Lavigne E, Zanobetti A,
Schwartz J, et al. Mortality risk attributable to high and low ambient
temperature: a multicountry observational study. Lancet. 2015;386:
36975.
13. Vardoulakis S, Dear K, Hajat S, Heaviside C, Eggen B, McMichael
A. Comparative assessment of the effects of climate change on heat-
and cold-related mortality in the United Kingdom and Australia.
Environ Health Perspect. 2014;122(12):128592.
14. Robine J-M, Cheung SLK, Le Roy S, Van Oyen H, Griffiths C,
Michel J-P, et al. Death toll exceeded 70,000 in Europe during the
summer of 2003. C R Biol. 2008;331:1718.
15. Le Tertre A, Lefranc A, Eilstein D, Declercq C, Medina S,
Blanchard M, et al. Impact of the 2003 heatwave on all-cause
mortality in 9 French cities. Epidemiology. 2005/12/17. 2006;17:
759.
16. Mitchell D, Heaviside C, Vardoulakis S, Huntingford C, Masato G,
Guillod BP, et al. Attributing human mortality during extreme heat
waves to anthropogenic climate change. Environ Res Lett. IOP
Publishing. 2016;11:74006.
17. Arnfield AJ. Two decades of urban climate research: a review of
turbulence, exchanges of energy and water, and the urban heat
island. Int J Climatol. 2003;23:126.
18. Stewart ID. A systematic review and scientific critique of method-
ology in modern urban heat island literature. Int J Climatol.
2011;31:20017.
19. Howard L. Climate of London deduced from meteorological obser-
vations. 3rd ed. London: Harvery and Darton; 1833.
20. Oke TR. City size and the urban heat island. Atmos Environ.
1973;7:76979.
21. Gedzelman SD, Austin S, Cermak R, Stefano N, Partridge S,
Quesenberry S, et al. Mesoscale aspects of the Urban Heat Island
around New York City. Theor Appl Climatol. 2003;75:2942.
22. Bohnenstengel SI, Evans S, Clark PA, Belcher SE. Simulations of
the London urban heat island. Q J R Meteorol Soc. 2011;137:1625
40.
23. Smith C, Webb A, Levermore GJ, Lindley SJ, Beswick K. Fine-
scale spatial temperature patterns across a UK conurbation. Clim
Chang. Springer Netherlands. 2011;109:26986.
24. Heaviside C, Cai XM, Vardoulakis S. The effects of horizontal
advection on the urban heat island in Birmingham and the West
Midlands, United Kingdom during a heatwave. Q J R Meteorol
Soc. John Wiley and Sons Ltd. 2015;141:142941.
25. Bassett R, Cai X, Chapman L, Heaviside C, Thornes JE, Muller CL,
et al. Observations of urban heat island advection from a high-
density monitoring network. Q J R Meteorol Soc. 2016;142(699):
243441.
26. Voelkel J, Shandas V, Haggerty B. Developing high-resolution de-
scriptions of urban heat islands: a public health imperative. Prev
Chronic Dis. Centers for Disease Control and Prevention (CDC);
2016;13.
27. Grimmond CSB, Oke TR, Grimmond CSB, Oke TR. Aerodynamic
properties of urban areas derived from analysis of surface form. J
Appl Meteorol. 1999;38:126292.
28. Martilli A, Clappier A, Rotach MW. An urban surface exchange
parameterisation for mesoscale models. Boundary-Layer Meteorol.
2002;104:261304.
29. DIppoliti D, Michelozzi P, Marino C, DeDonato F, Menne B,
Katsouyanni K, et al. The impact of heat waves on mortality in 9
European cities: results from the EuroHEAT project. Environ
Health. 2010;9:37.
30. Hajat S, Vardoulakis S, Heaviside C, Eggen B, Vardoulakis S,
Heaviside C, et al. Climate change effects on human health: projec-
tions of temperature-related mortality for the UK during the 2020s,
2050s and 2080s. J Epidemiol Community Health. BMJ Publishing
Group. 2014;68:6418.
Curr Envir Health Rpt
31. Li D, Bou-Zeid E. Synergistic interactions between urban heat
islands and heat waves: the impact in cities is larger than the sum
of its parts. J Appl Meteorol Climatol. 2013;52:205164.
32. Laaidi K, Zeghnoun A, Dousset B, Bretin P, Vandentorren S,
Giraudet E, et al. The impact of heat islands on mortality in Paris
during the August 2003 heat wave. Environ Health Perspect.
2012;120:2549.
33. ONeill MS, Ebi KL. Temperature extremes and health: impacts of
climate variability and change in the United States. J Occup
Environ Med. 2009;51:1325.
34. Huang C, Barnett AG, Wang X, Vaneckova P, FitzGerald G, Tong
S. Projecting future heat-related mortality under climate change
scenarios: a systematic review. Env Heal Perspect. 2011/08/06.
2011;119:168190.
35. Vardoulakis S, Dimitroulopoulou C, Thornes J, Lai KM, Taylor J,
Myers I, et al. Impact of climate change on the domestic indoor
environment and associated health risks in the UK. Environ Int.
Elsevier Ltd. 2015;85:299313.
36.Heaviside C, Vardoulakis S, Cai X-MM. Attribution of mortality to
the urban heat island during heatwaves in the West Midlands, UK.
Environ Health. 2016;15:4959. This case study is the first to
estimate number of heat wave deaths directly attributable to
the UHI effect for current and future climate, using health im-
pact assessment and regional meteorological modelling
techniques
37. Fischer EM, Oleson KW, Lawrence DM. Contrasting urban and
rural heat stress responses to climate change. Geophys. Res. Lett.
2012;39(3):L03705.
38. Mitchell BC, Chakraborty J. Urban heat and climate justice: a land-
scape of thermal inequity in Pinellas County. Florida Geogr Rev.
Wiley-Blackwell. 2014;104:45980.
39. Harlan SL, Brazel AJ, Jenerette GD, Jones NS, Larsen L, Prashad
L, et al. In the shade of affluence: the inequitable distribution of the
urban heat island. In: Equity and the Environment. Emerald Group
Publishing Limited. 2007;15:173-202.
40. HuangG, Cadenasso ML. People, landscape, and urban heat island:
dynamics among neighborhood social conditions, land cover and
surface temperatures. Landsc Ecol. Springer Netherlands. 2016;31:
250715.
41. Huang G, Zhou W, Cadenasso ML. Is everyone hot in the city?
Spatial pattern of land surface temperatures, land cover and neigh-
borhood socioeconomic characteristics in Baltimore, MD. J
Environ Manag. 2011;92:17539.
42. Hatvani-Kovacs G, Belusko M, Skinner N, Pockett J, Boland J.
Drivers and barriers to heat stress resilience. Sci Total Environ.
Elsevier. 2016;571:60314.
43. Mavrogianni A, Wilkinson P, Davies M, Biddulph P, Oikonomou
E. Building characteristics as determinants of propensity to high
indoor summer temperatures in London dwellings. Build Environ.
2012;55:11730.
44. Buscail C, Upegui E, Viel JF. Mapping heatwave health risk at the
community level for public health action. Int. J. Health Geogr.
2012;11:38.
45. Guo Y, Barnett AG, Tong S. Spatiotemporal model or time series
model for assessing city-wide temperature effects on mortality?
Environ Res. 2013;120:5562.
46. Dong W, Liu Z, Zhang L, Tang Q, Liao H, Li X. Assessing heat
health risk for sustainability in Beijings urban heat island. Sustain.
2014;6(10):733457.
47. Tomlinson CJ, Chapman L, Thornes JE, Baker CJ. Including the
urban heat island in spatial heat health risk assessment strategies: a
case study forBirmingham, UK. Int J Health Geogr. 2011;10(1):42.
48. Macintyre Heaviside C, Vardoulakis SH. Modelling the health im-
pacts of the Urban Heat Island, and the potential benefits of miti-
gation interventions in a UK city. In International Conference on
Urban Risks, CERU. Lisbon: European Centre on Urban Risk;
2016.
49. Weber S, Sadoff N, Zell E, de Sherbinin A. Policy-relevant indica-
tors for mapping the vulnerability of urban populations to extreme
heat events: a case study of Philadelphia. Appl Geogr. 2015;63:
23143.
50. Wolf T, McGregor G. The development of a heat wave vulnerability
index for London, United Kingdom. Weather Clim Extrem.
Elsevier. 2013;1:5968.
51.Taylor J, Wilkinson P, Davies M, Armstrong B, Chalabi Z,
Mavrogianni A, et al. Mapping the effects of urban heat island,
housing, and age on excess heat-related mortality in London.
Urban Clim. 2015;14:51728. This paper uses mapping and
quantitative estimates to estimate heat-related mortality driven
by a range of factors for London
52. Johnson DP, Wilson JS. The socio-spatial dynamics of extreme
urban heat events: the case of heat-related deaths in Philadelphia.
Appl Geogr. 2009;29:41934.
53. Hondula DM, Barnett AG. Heat-related morbidity in Brisbane,
Australia: spatial variation and area-level predictors. Environ
Health Perspect. Public Health Services, US Dept of Health and
Human Services. 2014;122:8316.
54. Hattis D, Ogneva-Himmelberger Y, Ratick S. The spatial variability
of heat-related mortality in Massachusetts. Appl Geogr. 2012;33:
4552.
55. Lowe SA. An energy and mortality impact assessment of the urban
heat islandin the US. Environ Impact Assess Rev. 2016;56:13944.
56. Smargiassi A, Goldberg MS, Plante C, Fournier M, Baudouin Y,
Kosatsky T. Variation of daily warm season mortality as a function
of micro-urban heat islands. J Epidemiol. Community Health.
2009;63:65964.
57. Goggins WB, Chan EYY, Ng E, Ren C, Chen L. Effect modifica-
tion of the association between short-term meteorological factors
and mortality by urban heat islands in Hong Kong. PLoS One.
2012;7(6):e38551.
58. Burkart K, Schneider A, Breitner S, Khan MH, Krämer A,
Endlicher W. The effect of atmospheric thermal conditions and
urban thermal pollution on all-cause and cardiovascular mortality
in Bangladesh. Environ Pollut. 2011;159:203543.
59. Kershaw SE, Millward AA. A spatio-temporal index for heat vul-
nerability assessment. Environ Monit Assess. 2012;184:732942.
60. Urban A, Davídkovová H, Kyselý J. Heat- and cold-stress effects
on cardiovascular mortality and morbidity among urban and rural
populations in the Czech Republic. Int J Biometeorol. Springer
New York LLC. 2014;58:105768.
61.Milojevic A, Armstrong BG, Gasparrini A, Bohnenstengel SI,
Barratt B, Wilkinson P. Methods to estimate acclimatization to ur-
ban heat island effects on heat-and cold-related mortality. Environ
Health Perspect. 2016;124:101622. Public Health Services, US
Dept of Health and Human Services. This paper looked at ad-
aptation to heat and cold in London based on different zones
depending on distance from centre and the UHI influence
62. Jenkins K, Hall J, Glenis V, Kilsby C, McCarthy M, Goodess C,
et al. Probabilistic spatial risk assessment of heat impacts and ad-
aptations for London. Clim Chang. Kluwer Academic Publishers.
2014;124:10517.
63. Arbuthnott K, Hajat S, Heaviside C, Vardoulakis S. Changes in
population susceptibility to heat and cold over time: assessing ad-
aptation to climate change. Environ Health. 2016;15:7393.
64.Hondula DM, Georgescu M, Balling RC. Challenges associ-
ated with projecting urbanization-induced heat-related mor-
tality. Sci Total Environ. 2014;490:53844. This paper
quantified heat-related deaths based on future urbanisa-
tion and adaptation scenarios using multiple exposure
variables
Curr Envir Health Rpt
65. Public Health England. Heatwave plan for England. 2015.
Available at https://www.gov.uk/government/publications/
heatwave-plan-for-england.
66. Harlan SL, Ruddell DM. Climate change and health in cities: im-
pacts of heat and air pollution and potential co-benefits from miti-
gation and adaptation. Curr Opin Environ Sustain. 2011;3:12634.
67. Akbari H, Kolokotsa D. Three decades of urban heat islands and
mitigation technologies research. Energy Build. Elsevier Ltd.
2016;133:83452.
68. Morini E, Touchaei AG, Castellani B, Rossi F, Cotana F. The im-
pact of albedo increase to mitigate the urban heat island in Terni
(Italy) using the WRF model. Sustain. MDPI AG; 2016;8(10):999.
69. Fallmann J, Forkel R, Emeis S. Secondary effects of urban heat
island mitigation measures on air quality. Atmos Environ.
Elsevier Ltd. 2016;125:199211.
70. Ng E, Chen L, Wang Y, Yuan C. A study on the cooling effects of
greening in a high-density city: an experience from Hong Kong.
Build. Environ. 2012;47:25671.
71. Oliveira S, Andrade H, Vaz T. The cooling effect of green spaces as
a contribution to the mitigation of urban heat: a case study in
Lisbon. Build. Environ. 2011;46:218694.
72. Knight T, Price S, Bowler D, King S. How effective is greening
of urban areas in reducing human exposure to ground-level ozone
concentrations, UV exposure and the urban heat island effect?A
protocol to update a systematic review. Environ. Evid. BioMed
Central Ltd.; 2016;5:3.
73.Bosch M Van Dev Nieuwenhuijsen M. No time to losegreen the
cities now. Environ. Int. 2016;99:34350. This review addresses a
wide range of considerations relating to urban greening, health
and wellbeing.
74. Burkart K, Meier F, Schneider A, Breitner S, Canário P, Alcoforado
MJ, et al. Modification of heat-related mortality in an elderly urban
population by vegetation (urban green) and proximity to water (ur-
ban blue): evidence from Lisbon, Portugal. Environmental Health
Perspectives. 2016;124(7):92734.
75. de Keijzer C, Agis D, Ambrós A, Arévalo G, Baldasano JM, Bande
S, et al. The association of air pollution and greenness with mortal-
ity and life expectancy in Spain: a small-area study. Environ. Int.
2016;99:1706.
76. Lee AC, Maheswaran R. The health benefits of urban green spaces:
a review of the evidence. J. Public Health (Bangkok). Oxford
University Press. 2011;33(2):21222.
77.Wheeler BW, Lovell R, Higgins SL, White MP, Alcock I, Osborne
NJ, et al. Beyond greenspace: an ecological study of population
general health and indicators of natural environment type and qual-
ity. Int J Health Geogr. 2015;14:117. This study explores the
different types of green space and the relationship with health
and wellbeing.
78. Price A, Jones EC, Jefferson F. Vertical greenery systems as a strat-
egy in Urban Heat Island mitigation. Water. Air. Soil Pollut. Kluwer
Academic Publishers; 2015;226(8):1-11.
79. Klein PM, Coffman R. Establishment and performance of an ex-
perimental green roof under extreme climatic conditions. Sci Total
Environ. Elsevier. 2015;512513:8293.
80. Karteris M, Theodoridou I, Mallinis G, Tsiros E, Karteris A.
Towards a green sustainable strategy for Mediterranean cities:
assessing the benefits of large-scale green roofs implementation in
Thessaloniki, Northern Greece, using environmental modelling,
GIS and very high spatial resolution remote sensing data. Renew
Sust Energ Rev. Elsevier Ltd. 2016;58:51025.
81. Razzaghmanesh M, Beecham S, Salemi T. The role of green roofs
in mitigating Urban Heat Island effects in the metropolitan area of
Adelaide, South Australia. Urban For Urban Green. 2016;15:89
102.
82. Phelan PE, Kaloush K, Miner M, Golden J, Phelan B, Silva III H,
et al. Urban Heat Island: mechanisms, implications, and possible
remedies.Annu. Rev. Environ. Resour. Annual Reviews Inc.; 2015.
p. 285307.
83.Salmond JJA, Tadaki M, Vardoulakis S, Arbuthnott K, Coutts A,
Demuzere M, et al. Health and climate related ecosystem services
provided by street trees in the urban environment. Environ Health.
2016;15:36. BioMed Central. This review covers a wide range
of ecosystem services provided by street trees, both in terms of
potential benefits as well as potential health risks
84. Che-Ani AI, Shahmohamadi P, Sairi A, Mohd-Nor MFI, Zain
MFM, Surat M. Mitigating the urban heat island effect: some points
without altering existing city planning. Eur J Sci Res. EuroJournals,
Inc. 2009;35:20416.
85. Champiat C. Heat island analysis to reduce the public health impact
of heat waves. Environnement, Risques et Sante. 2009;8:399411.
86. Woods M, Crabbe H, Close R, Studden M, Milojevic A, Leonardi
G, et al. Decision support for risk prioritisation of environmental
health hazards in a UK city. Environ Heal. 2016;15(Suppl 1):S29.
87. Vargo J, Stone B, Habeeb D, Liu P, Russell A. The social and spatial
distribution of temperature-related health impacts from urban heat
island reduction policies. Environ Sci Pol. Elsevier Ltd. 2016;66:
36674.
88. ONeill MS, Jackman DK, Wyman M, Manarolla X, Gronlund CJ,
Brown DG, et al. US local action on heat and health: are we pre-
pared for climate change? Int J Public Health. 2010;55:10512.
89. Buchin O, Hoelscher MT, Meier F, Nehls T, Ziegler F. Evaluation of
the health-risk reduction potential of countermeasures to urban heat
islands. Energy Build Elsevier Ltd. Elsevier Ltd. 2016;114:2737.
90. Boumans RJM, Phillips DL,Victery W, Fontaine TD. Developing a
model for effects of climate change on human health and health-
environment interactions: heat stress in Austin, Texas,Urban Clim.
Elsevier. 2014;8:7899.
91. Susca T. Multiscale approach to life cycle assessment: evaluation of
the effect of an increase in New York Citys Rooftop Albedo on
Human Health Susca, LCA: Rooftop Albedo and Human Health. J
Ind Ecol. 2012;16:95162.
92.Stone Jr B, Vargo J, Liu P, Habeeb D, DeLucia A, Trail M, et al.
Avoided heat-related mortality through climate adaptation strate-
gies in three US cities. PLoS One. Public Library of Science;
2014;9(6):e100852. This paper used a range of adaptation strat-
egies to quantify the health benefits through reduced mortality.
93. Silva HR, Phelan PE, Golden JS. Modeling effects of urban heat
island mitigation strategies on heat-related morbidity: a case study
for Phoenix, Arizona, USA. Int J Biometeorol. 2010;54:1322.
94. Chen D, Wang X, Thatcher M, Barnett G, Kachenko A, Prince R.
Urban vegetation for reducing heat related mortality. Environ
Pollut. Elsevier Ltd. 2014;192:27584.
95.Sailor D, Shepherd M, Sheridan S, Stone B, Kalkstein L, Russell A,
et al. Improving heat-related health outcomes in an Urban environ-
ment with science-based policy. Sustain. 2016;8(10):1015. This
paper uses a case study to explore how to improve links be-
tween science and policy in relation to the UHI effect.
96. Wolf T, Chuang W-C, McGregor G. On the science-policy bridge:
do spatial heat vulnerability assessment studies influence policy?
Int J Environ Res. Public Health. Multidisciplinary Digital
Publishing Institute. 2015;12:1332149.
Curr Envir Health Rpt
... Global temperatures are expected to rise by 1.0-3.7°C in the twenty-first century, depending on future greenhouse gas emissions (Abulibdeh, 2021;Anderson, Hawkins, & Jones, 2016;Fawzy, Osman, Doran, & Rooney, 2020). Global warming has pushed more people into urban areas, and a growing population can increase the dangers of living in a hot environment (Heaviside, Macintyre, & Vardoulakis, 2017). The urban heat island (UHI) effect occurs when city temperatures are consistently higher than suburban ones (Lee, Kim, Sung, Ryu, & Jeon, 2019;Masumoto, 2015;Zhou et al., 2018). ...
... The urban heat island (UHI) effect occurs when city temperatures are consistently higher than suburban ones (Lee, Kim, Sung, Ryu, & Jeon, 2019;Masumoto, 2015;Zhou et al., 2018). Understanding future temperature changes in cities necessitates an understanding of the combined effects of urbanization and climate change (Chapman, Watson, Salazar, Thatcher, & McAlpine, 2017;Heaviside et al., 2017). UHI causes thermal discomfort, increases energy consumption, and degrades public health (lowering quality of life) (Aram, Solgi, Garcia, & Mosavi, 2020;Filho et al., 2021;Sen & Khazanovich, 2021). ...
Article
Full-text available
Since the nineteenth century, scientists have studied the Urban Heat Island (UHI). The negative effects of UHI could be mitigated with the help of interdisciplinary studies, but none have been performed so far. UHI research in schools has some holes that could seriously hinder students' grasp of climate change. The purpose of this research is to ascertain whether or not the Urban Heat Island module is necessary for enhancing students' understanding of climate change in the classroom. The Greater Solo Area Region's 72 geographic teachers were chosen at random for this study. Preliminary data on teachers' familiarity with UHI in the Greater Solo Area shows that, on average, they know very little about UHI. About 47 percent of the teachers surveyed had no understanding at all of UHI, while the remaining 25 percent had a moderate amount of knowledge, seven percent had high understanding, and three percent had very high understanding. Results from a test given to educators in both the suburbs and the city corroborated these observations. All teachers agreed that the UHI enrichment module created using a contextual approach was necessary as a supplementary medium for climate change material, as indicated by the results of the teacher needs assessment tests.
... Particular attention has been given to urban heat because temperature is a reliably measured weather variable, known to have negative impacts on health, buildings and infrastructure, energy, or biodiversity 2-6 . Considering public health alone, hotter urban areas are subject to higher levels of heat-related mortality and morbidity, such as risk of stroke, exhaustion, and cardiovascular diseases 7,8 . Therefore, understanding which urban environments are most associated with extreme heat, and the underlying vulnerabilities of their inhabitants, is necessary to establish sustainable and healthy cities. ...
Article
Full-text available
Personal weather stations (PWS) can provide useful data on urban climates by densifying the number of weather measurements across major cities. They do so at a lower cost than official weather stations by national meteorological services. Despite the increasing use of PWS data, little attention has yet been paid to the underlying socio-economic and environmental inequalities in PWS coverage. Using social deprivation, demographic, and environmental indicators in England and Wales, we characterize existing inequalities in the current coverage of PWS. We find that there are fewer PWS in more deprived areas which also observe higher proportions of ethnic minorities, lower vegetation coverage, higher building height and building surface fraction, and lower proportions of inhabitants under 65 years old. This implies that data on urban climate may be less reliable or more uncertain in particular areas, which may limit the potential for climate adaptation and empowerment in those communities.
... Another factor that causes the UHI effect is the urban geometry formed by high-rise buildings that alter the air dynamics in between street canyons, which potentially prevents cool prevailing winds from entering the core of the city and limits natural ventilation for cooling [4]. Many studies have mentioned the potential risks that urban heat poses to human health and well-being, which can be fatal under extremely hot weather events [5,6]. To overcome the issues of increased urban heat situations, most urban dwellers excessively rely on the use of HVAC systems, which, however, increases energy consumption and greenhouse gas emissions in the long term. ...
Article
Full-text available
Under the current energy crisis and climate change, sustainable urban planning and building design are a priority to achieve a net-zero future, as energy use in buildings for thermal comfort is one of the major carbon emission contributors. To adapt to a rapidly growing and stringent urban environment, where buildings are causing more emissions due to more frequent and severe extreme hot weather events, the parametric design approach has great potential and flexibility in providing a sustainable solution by simulating different design scenarios. This study aims to analyse urban geometry and identify the impact of various built environment scenarios on outdoor thermal comfort under certain climates. The Grasshopper program was used along with the Ladybugs plug-in to provide visualised outcomes of outdoor thermal comfort, with simulation models on Rhinoceros 3D Version 7 SR37 (7.37.24107.1500). Comparing the thermal comfort performance of different design scenarios, based on building height, orientation and urban geometry, helps to identify which factors are more impactful on building design. This study demonstrates the workflow of parametric design in analysing the microclimate pattern and outdoor thermal comfort performance of the existing built environment in Melbourne, Australia, to provide an insight for stakeholders and builders to inform better decision-making in urban planning and building design in order to achieve a zero-emission future.
... Urban heat island (UHI) is a commonly watched phenomenon around the world which is an urban area with significantly higher temperatures than those within the encompassing regions(de Groot-Reichwein et al., 2018;Lee et al., 2020;Wang et al., 2019). Moreover, (Heaviside, Macintyre, & Vardoulakis, 2017) argued that the UHI escalated, for the most part, characterized by the difference in air temperature between built-up urban areas and rural areas) within the urban canopy, the layer is more articulated at night time, when it can reach values of up to 10 °C in large cities. A sampling of teachers based on the distribution of school locations is expected to describe the urban heat island media needs of urban and rural teachers. ...
Article
Full-text available
Nowadays, Urban Heat Island (UHI) occurs in big cities worldwide. The UHI phenomenon needs to be introduced in school because this phenomenon occurs around the students. Surakarta, one of the big cities in Indonesia, has been threatened by the UHI phenomenon, so enrichment materials related to the UHI phenomenon are needed for students in schools. This research will develop the UHI e-module as an enrichment teaching material on the impact of global climate change and research on climate and its utilization. This paper aims to present an e-module development research methodology on UHI based on the phenomenon of UHI threats in Surakarta City and its effect on student achievement and collaboration skills. Design and Development Research (DDR) uses the Borg and Gall model. The methodology of the research development is divided into three phases: the needs analysis phase, the design and development phase, and the implementation and evaluation phases. The difference in this research is the geographical space-based study approach in the development of material based on the UHI phenomenon in Surakarta City and urban and rural spatial sampling techniques.
... Urban heat island (UHI) is a commonly watched phenomenon around the world which is an urban area with significantly higher temperatures than those within the encompassing regions(de Groot-Reichwein et al., 2018;Lee et al., 2020;Wang et al., 2019). Moreover, (Heaviside, Macintyre, & Vardoulakis, 2017) argued that the UHI escalated, for the most part, characterized by the difference in air temperature between built-up urban areas and rural areas) within the urban canopy, the layer is more articulated at night time, when it can reach values of up to 10 °C in large cities. A sampling of teachers based on the distribution of school locations is expected to describe the urban heat island media needs of urban and rural teachers. ...
Article
Full-text available
Nowadays, Urban Heat Island (UHI) occurs in big cities worldwide. The UHI phenomenon needs to be introduced in school because this phenomenon occurs around the students. Surakarta, one of the big cities in Indonesia, has been threatened by the UHI phenomenon, so enrichment materials related to the UHI phenomenon are needed for students in schools. This research will develop the UHI e-module as an enrichment teaching material on the impact of global climate change and research on climate and its utilization. This paper aims to present an e-module development research methodology on UHI based on the phenomenon of UHI threats in Surakarta City and its effect on student achievement and collaboration skills. Design and Development Research (DDR) uses the Borg and Gall model. The methodology of the research development is divided into three phases: the needs analysis phase, the design and development phase, and the implementation and evaluation phases. The difference in this research is the geographical space-based study approach in the development of material based on the UHI phenomenon in Surakarta City and urban and rural spatial sampling techniques.
Chapter
Stewart and Oke introduced the local climate zone (LCZ) scheme that has over the past decade garnered global recognition for being the most meticulous land classification system yet. LCZ illustrates classes and sub-classes that are local in scale, climatic in nature and zonal in representation. The LCZ framework comprehensively analyses the influence of morphological parameters and anthropogenic activities on the urban environment. The immensely disturbed environment is the aftermath of human-induced (mostly irreversible) alterations across micro, local and meso scales. Extensive land use and land cover transformations coupled with mushrooming population are rapidly transforming cityscapes and the climatic regime globally. A growing body of literature has established multifarious impacts of intensifying heat in urban areas. This has led the researchers to invent and hone systems that categorize land, interpret the climatic variabilities and thus combat vulnerabilities. This chapter deliberates upon three key aspects: (1) urban configuration and the magnitude of UHI in high-density cities; (2) various spatial classification frameworks and (3) applicability of LCZ scheme through multiple investigations conducted globally. Congested LCZs experience elevated temperatures at the canopy and surface level during the night whereas the sparsely-built LCZs record much lower temperature both during the day and night.
Article
The Urban Heat Island (UHI), which causes urban areas to be warmer than rural counterparts, impacts buildings' energy demands for heating and cooling. Conventional weather data, typically gathered at non-urban sites like airports, are used to create Typical Meteorological Year (TMY) files for building energy assessments. However, this data doesn't account for urban temperature effects, impacting the accuracy of these assessments. This study proposes a novel methodology that couples Local Climate Zones (LCZs) with the Urban Weather Generator (UWG) to produce urban-specific weather data reflecting UHI effects for more accurate energy simulations. LCZs categorize urban neighborhoods into landscape types based on building heights, proximity, greenspace, etc., which regulate the magnitude of the UHI. The UWG uses LCZ parameters to estimate UHI intensity based on existing weather conditions. Together, they generate city-specific TMY files tailored to individual neighborhoods. Here, modified TMY files for seven U.S. cities located in different climates, were generated and used in residential building energy simulations. The UHI effect increases Cooling Degree Days (CDD) and decreases Heating Degree Days (HDD), but energy demand impacts vary by city and LCZ type. This methodology provides a simple means for incorporating the impact of UHI into building and urban energy simulations.
Article
Full-text available
The likelihood of exposure to overheated indoor environments is increasing as climate change is exacerbating the frequency and severity of hot weather and extreme heat events (EHE). Consequently, vulnerable populations will face serious health risks from indoor overheating. While the relationship between EHE and human health has been assessed in relation to outdoor temperature, indoor temperature patterns can vary markedly from those measured outside. This is because the built environment and building characteristics can act as an important modifier of indoor temperatures. In this narrative review, we examine the physiological and behavioral determinants that influence a person’s susceptibility to indoor overheating. Further, we explore how the built environment, neighborhood-level factors and building characteristics can impact exposure to excess heat and overview how strategies to mitigate building overheating can help reduce heat-related mortality in heat-vulnerable occupants. Finally, we discuss the effectiveness of commonly recommended personal cooling strategies that aim to mitigate dangerous increases in physiological strain during exposure to high indoor temperatures during hot weather or an EHE. As global temperatures continue to rise, the need for a research agenda specifically directed at reducing the likelihood and impact of indoor overheating on human health is paramount. This includes conducting EHE simulation studies to support the development of consensus-based heat mitigation solutions and public health messaging that provides equitable protection to heat-vulnerable people exposed to high indoor temperatures.
Article
Full-text available
We use the Northeast US Urban Climate Archipelago as a case study to explore three key limitations of planning and policy initiatives to mitigate extreme urban heat. These limitations are: (1) a lack of understanding of spatial considerations-for example, how nearby urban areas interact, affecting, and being affected by, implementation of such policies; (2) an emphasis on air temperature reduction that neglects assessments of other important meteorological parameters, such as humidity, mixing heights, and urban wind fields; and (3) too narrow of a temporal focus-either time of day, season, or current vs. future climates. Additionally, the absence of a direct policy/planning linkage between heat mitigation goals and actual human health outcomes, in general, leads to solutions that only indirectly address the underlying problems. These issues are explored through several related atmospheric modeling case studies that reveal the complexities of designing effective urban heat mitigation strategies. We conclude with recommendations regarding how policy-makers can optimize the performance of their urban heat mitigation policies and programs. This optimization starts with a thorough understanding of the actual end-point goals of these policies, and concludes with the careful integration of scientific knowledge into the development of location-specific strategies that recognize and address the limitations discussed herein.
Article
Full-text available
The impacts of the urban heat island (UHI) phenomenon on energy consumption, air quality, and human health have been widely studied and described. Mitigation strategies have been developed to fight the UHI and its detrimental consequences. A potential countermeasure is the increase of urban albedo by using cool materials. Cool materials are highly reflective materials that can maintain lower surface temperatures and thus can present an effective solution to mitigate the UHI. Terni’s proven record of high temperatures along with related environmental and comfort issues in its urban areas have reflected the local consequences of global warming. On the other hand, it promoted integrated actions by the government and research institutes to investigate solutions to mitigate the UHI effects. In this study, the main goal is to investigate the effectiveness of albedo increase as a strategy to tackle the UHI, by using the Weather Research and Forecasting (WRF) mesoscale model to simulate the urban climate of Terni (Italy). Three different scenarios through a summer heat wave in the summer of 2015 are analyzed. The Base Scenario, which simulates the actual conditions of the urban area, is the control case. In the Albedo Scenario (ALB Scenario), the albedo of the roof, walls and road of the whole urban area is increased. In the Albedo-Industrial Scenario (ALB-IND Scenario), the albedo of the roof, walls and road of the area occupied by the main industrial site of Terni, located in close proximity to the city center, is increased. The simulation results show that the UHI is decreased up to 2 °C both at daytime and at nighttime in the ALB and in ALB-IND Scenarios. Peak temperatures in the urban area can be decreased by 1 °C at daytime, and by about 2 °C at nighttime. Albedo increase in the area of interest might thus represent an opportunity to decrease the UHI effect and its consequences.
Article
Full-text available
Extreme heat events affect the most vulnerable human populations and are a lethal health hazard to urban dwellers globally; in the United States, extreme heat causes more deaths annually than all other weather events and natural hazards combined (1). Previous studies described urban heat islands as isolated, static, monolithic areas of cities. We challenged this contention by hypothesizing that diurnal temperature cycles and diverse landscape features create variation in places that amplify heat (2). A temporal description of urban heat islands would identify populations that are susceptible to heat stress, particularly at night, when most people are asleep and unable to regulate internal body temperatures. If public health agencies are to prevent illness and death caused by heat, they will need to know which populations are most vulnerable to heat stress, particularly at night; such information can guide timely interventions (3). Researchers lack high-resolution tools for identifying neighborhoods and households where extreme weather events might have profound and fatal effects on human health. The objective of this study was to use spatial analytics at previously unattained resolutions to answer the following research question: to what extent can we observe temporal variation in urban heat islands and the physical features that induce heat stress?.
Article
Full-text available
ContextUrban heat island studies have found that land cover, neighborhood social conditions and temperatures are correlated. This received great academic attention because of potential ecological, social and health impacts. However, the processes and causalities behind such correlations remain unclear, which impede designing effective heat mitigation approaches. Objectives Our study aims to answer two questions: (1) Do social conditions influence temperature independent of land cover? (2) Is land cover more closely associated with temperature than neighborhood social conditions or vice versa? Methods The analysis is for the year 2000 and the Gwynns Falls watershed in Baltimore, Maryland. Census data for 297 block groups and remote sensed data for land cover and surface temperature were used. To answer question 1, we used structural equation modeling to build and compare model fitness. We conducted partial correlation and regression analysis to answer question 2. ResultsLand cover (building and trees) leads both social conditions (race and income) and temperature to vary across space. When holding land cover constant, social conditions significantly contribute to temperature variation. Conclusions This study extends understanding beyond simple correlation and determined that land cover influences the spatial variation in neighborhood social conditions and temperature.
Book
The 'student of clouds' Luke Howard (1772–1864) published this work of statistics on weather conditions in London in two volumes, in 1818 and 1820. Howard was by profession an industrial chemist, but his great interest in meteorology led to his studies on clouds (also reissued in this series), and his devising of the system of Latin cloud names which was adopted internationally and is still in use. Volume 1 begins with an introduction to the work, explaining his intention to make available in one place consistent records of weather events. He argues that for the benefit of 'agriculture and navigation', a systematic approach is required, and he outlines his methods and equipment in some detail. The tables of observations taken at Plaistow, near London, in the years 1806–9 then begin, and are interspersed with notes and a commentary which includes accounts of similar weather phenomena observed elsewhere.
Article
¶A mesoscale analysis of the Urban Heat Island (UHI) of New York City (NYC) is performed using a mesoscale network of weather stations. In all seasons the UHI switches on rapidly in late afternoon and shuts down even more rapidly shortly after dawn. It averages about 4 °C in summer and autumn and 3 °C in winter and spring. It is largest on nights with clear skies, low relative humidity through much of the troposphere, and weak northwest winds, when it may exceed 8 °C. The synoptic meteorological situation associated with the largest UHI occurs roughly two to three nights after cold front passages. During spring and summer, sea breezes commonly reduce and delay the UHI and displace it about 10 km to the west. Backdoor cold fronts, which occur most frequently in spring and early summer, reduce or even reverse the UHI, as cold air from the water to the northeast keeps NYC colder than the western suburbs. Cases documenting the sensitivity and rapidity of changes of the UHI to changes in parameters such as cloud cover, ceiling, and wind speed and direction are presented.
Article
http://www.sciencedirect.com/science/article/pii/S0160412016308996 The world is rapidly urbanising, especially in developing regions. Although city living implies many advantages, such as job opportunities and cultural and health services, the urban environment also imposes particular health risks. These are connected to various environmental exposures, such as air pollution, heat, noise, and lack of natural areas offering space for recreation and physical activity, with subsequent high prevalence of non-communicable diseases and climate change related morbidity. An increasing amount of research shows that investments in urban natural (green and blue) areas may be an efficient option for mitigating some of those environmental risks and for promoting human health. In this paper we evaluate existing research on health impacts associated with urban natural spaces, including co-benefits to the environment. We aim to increase the understanding of why green investments and solutions are not sufficiently applied, by reviewing potential obstacles, such as cognitive bias, poor translation of science in to policy, academic traditions, and economic constraints. We conclude that the probability of net-benefits to both health and urban ecosystems by natural spaces is very high and that increased efforts are required to translate this knowledge into policy and practice, especially in developing parts of the world.
Article
Background: Air pollution exposure has been associated with an increase in mortality rates, but few studies have focused on life expectancy, and most studies had restricted spatial coverage. A limited body of evidence is also suggestive for a beneficial association between residential exposure to greenness and mortality, but the evidence for such an association with life expectancy is still very scarce. Objective: To investigate the association of exposure to air pollution and greenness with mortality and life expectancy in Spain. Methods: Mortality data from 2148 small areas (average population of 20,750 inhabitants, and median population of 7672 inhabitants) covering Spain for years 2009-2013 were obtained. Average annual levels of PM10, PM2.5, NO2 and O3 were derived from an air quality forecasting system at 4×4km resolution. The normalized difference vegetation index (NDVI) was used to assess greenness in each small area. Air pollution and greenness were linked to standardized mortality rates (SMRs) using Poisson regression and to life expectancy using linear regression. The models were adjusted for socioeconomic status and lung cancer mortality rates (as a proxy for smoking), and accounted for spatial autocorrelation. Results: The increase of 5μg/m3 in PM10, NO2 and O3 or of 2μg/m3 in PM2.5 concentration resulted in a loss of life in years of 0.90 (95% credibility interval CI: 0.83, 0.98), 0.13 (95% CI: 0.09, 0.17), 0.20years (95% CI: 0.16, 0.24) and 0.64 (0.59, 0.70), respectively. Similar associations were found in the SMR analysis, with stronger associations for PM2.5 and PM10, which were associated with an increased mortality risk of 3.7% (95% CI: 3.5%, 4.0%) and 5.7% (95% CI: 5.4%, 6.1%). For greenness, a protective effect on mortality and longer life expectancy was only found in areas with lower socioeconomic status. Conclusions: Air pollution concentrations were associated to important reductions in life expectancy. The reduction of air pollution should be a priority for public health.
Article
Although the urban heat island (UHI) phenomena phenomenon has was been documented over a century ago, the effect of the urban heat island on urban climate and environment during the summer have only been the focus of research over the last three decades. One main characteristics of the recent research has been to evaluate the summertime effects of UHI on energy use, air pollution, outdoor ambient temperature, and citizen health. The second aspect of the recent research has been the development and evaluation of materials to counter the effects of summertime UHI. This paper provides a selective representation (by topic) review of the research on the development and evaluation of mitigation measures, including: cool roofs, cool pavements, and urban vegetation.
Article
Cities are developing innovative strategies to combat climate change but there remains little knowledge of the winners and losers from climate-adaptive land use planning and design. We examine the distribution of health benefits associated with land use policies designed to increase vegetation and surface reflectivity in three US metropolitan areas: Atlanta, GA, Philadelphia, PA, and Phoenix, AZ. Projections of population and land cover at the census tract scale were combined with climate models for the year 2050 at 4 km × 4 km resolution to produce future summer temperatures which were input into a comparative risk assessment framework for the temperature-mortality relationship. The findings suggest disparities in the effectiveness of urban heat management strategies by age, income, and race. We conclude that, to be most protective of human health, urban heat management must prioritize areas of greatest population vulnerability.