Review and Critical Analysis of International UHI Studies

temperature and climate, thus changing a diseases geography, seasonality and infection
frequency [129].
There are many papers looking at mortality rates during heat‐waves, the elderly appear to be the
highest risk group [078, 089, 117, 129, 130].
A study undertaken after a heat wave in the summer of 2003 in Italy analyzed death records for
that period and compared them to the same period for the previous year in the 21 Italian regional
capitals. The results confirmed that there had been an increase in mortality by 3,134 and 92% of
those deaths were aged over 75 years old, which was more than a 20% increase. The highest
increases occurred in the over 75’s in the northwestern cities which typically experience cooler
weather. This study was asked to be undertaken at relatively short notice and so the data may not
have been complete and due to time constraints only compared to one year prior to the event
[117].
A heat wave in France in the summer of 2003 recorded 14,802 excess deaths compared to the
same period in the three years prior. Again the age group with the largest increase was the over
75s [130].
A study of the July 2006 heat‐wave in California, as well as air temperature, weather and ozone
levels were accounted for, results showed a daily mortality rate increase of 9% per 10°F, this is 3
times greater than for full summer non heat‐wave seasons [131]. Heat waves are often associated
with high levels of air pollution [130].
When examining heat‐wave related deaths it is important to consider other indirect causes,
where there is perhaps not such a defined cause of death. Studies suggest that often mortality
rates in heat waves are often underestimated [131].
Temperature increases have also been linked, although somewhat controversially, to violent
crime, heat can make humans more aggressive and irritable, one study in the USA found that for
every 1°F increase in temperature violent crimes (murders and assaults) increased by 4.58/100,000
[174].
2.2.7 Economic Impacts
Many papers discuss the impacts of urban heat islands on human health, air quality and green
house gases and energy consumption but few discuss the impacts to the economy.
We know from previous sections that rising temperatures increase the demand for cooling in the
use of air‐conditioning units and fans. In the US a sixth of all electricity generated was used to air
condition buildings, this equates to approximately $40 billion a year in energy bills of which
about half occurs in cities that have been classed urban heat islands [080, figures from 2001].
Extreme weather events such as heat waves can have devastating effects upon the economy. In
Europe, in 2003 the heat wave caused 35,000 deaths and agricultural losses of $15bn across three
countries. The losses incurred by extreme weather events are rising, according to the Stern
Review: Economics of Climate Change. In 2005, globally annual damage/losses were reported to
be as much as $184 billion from windstorms alone [175].
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