Relationship between thermal index and mortality in Hong Kong

In summer (May–September), deaths associated with heat stroke are found to occur when the daily maximum net effective temperature (NET) exceeds 26. Using Poisson regression, it is estimated that the mean mortality associated with heat stroke would double per unit rise in NET beyond 26. In contrast to those in most temperate regions, the daily mortality for circulatory and respiratory related causes of death is not statistically correlated to the daily maximum NET or temperature in summer. In winter (November–March), there are statistically significant negative-lagged correlations between the daily minimum NET and the daily mortality attributed to circulatory and respiratory diseases. The increase in mortality per unit decrease in NET is found to be the highest for hypothermia, and slightly higher for circulatory causes than respiratory causes. Deaths associated with hypothermia start to occur when the daily minimum NET is less than 14 and the mean mortality is estimated to increase by about 1.3-fold per unit fall in NET below 14. The elderly age group (age ≧ 65 years) is found to be more vulnerable to NET changes when compared to other age groups. Copyright © 2008 Royal Meteorological Society