International study of temperature, heat and urban mortality: the 'ISOTHURM' project.
BACKGROUND
This study describes heat- and cold-related mortality in 12 urban populations in low- and middle-income countries, thereby extending knowledge of how diverse populations, in non-OECD countries, respond to temperature extremes.


METHODS
The cities were: Delhi, Monterrey, Mexico City, Chiang Mai, Bangkok, Salvador, São Paulo, Santiago, Cape Town, Ljubljana, Bucharest and Sofia. For each city, daily mortality was examined in relation to ambient temperature using autoregressive Poisson models (2- to 5-year series) adjusted for season, relative humidity, air pollution, day of week and public holidays.


RESULTS
Most cities showed a U-shaped temperature-mortality relationship, with clear evidence of increasing death rates at colder temperatures in all cities except Ljubljana, Salvador and Delhi and with increasing heat in all cities except Chiang Mai and Cape Town. Estimates of the temperature threshold below which cold-related mortality began to increase ranged from 15 degrees C to 29 degrees C; the threshold for heat-related deaths ranged from 16 degrees C to 31 degrees C. Heat thresholds were generally higher in cities with warmer climates, while cold thresholds were unrelated to climate.


CONCLUSIONS
Urban populations, in diverse geographic settings, experience increases in mortality due to both high and low temperatures. The effects of heat and cold vary depending on climate and non-climate factors such as the population disease profile and age structure. Although such populations will undergo some adaptation to increasing temperatures, many are likely to have substantial vulnerability to climate change. Additional research is needed to elucidate vulnerability within populations.
National Centre for Epidemiology and Population Health, The Australian National University College of Medicine and Health Sciences, Canberra, Australia.
Anthony J
AJ
McMichael
Paul
P
Wilkinson
R Sari
RS
Kovats
Sam
S
Pattenden
Shakoor
S
Hajat
Ben
B
Armstrong
Nitaya
N
Vajanapoom
Emilia M
EM
Niciu
Hassan
H
Mahomed
Chamnong
C
Kingkeow
Mitja
M
Kosnik
Marie S
MS
O'Neill
Isabelle
I
Romieu
Matiana
M
Ramirez-Aguilar
Mauricio L
ML
Barreto
Nelson
N
Gouveia
Bojidar
B
Nikiforov
D000222:Adaptation, Physiological; D000397:Air Pollution; D002423:Cause of Death; D002980:Climate; D003080:Cold Temperature; D003906:Developing Countries; D006358:Hot Temperature; D006801:Humans; D006813:Humidity; D016014:Linear Models; D009026:Mortality; D012044:Regression Analysis; D012621:Seasons; D012931:Social Environment; D013696:Temperature; D014505:Urban Population