Impact of high temperature on the mortality in summer of Wuhan, China

High temperature and heat waves are linked to excess mortality and morbidity and have been increasing in frequency and intensity along with a warming climate. The present study aimed to investigate the relationship between daily maximum temperature and all-cause mortality in Wuhan, China, during the summers of 2005-2012. Differences in mortality rate between heat wave (HW) and non-heat wave days were examined using t test and the responses of different age groups and genders during heat waves were examined using paired t test. Results showed that excess mortality of residents was significantly positively correlated with high temperature in the summer of Wuhan City. Both mortalities for aged male and female (above 64 years old) were sensitive to the temperature change, while in the young group (around 14-64 years old), only the males were sensitive. The extreme mortality associated with temperature increases was approximately a logarithmic curve. Among the low, moderate and high HW, the mortality rate under the moderate HW was the greatest. Within 1 year, the highest mortality rate typically occurred when encountering the first to third HW event and the mortality rate decreased after three HW events. Another interesting finding was that the highest mortality rate of young groups often occurred in the first and third day of a HW, while that of the aged groups was in the second and fourth day.