Heat-related mortality in Moldova: the summer of 2007

Heat waves of 2007 in Chisinau (Moldova) were used to study the relationship between elevated temperatures and excess mortality caused by these events. As reference information, daily temperature and mortality data for an 8-year reference period (2000-2008 without 2007) were used. Mean (T-mean), maximum (T-max) and minimum (T-min) daily air temperatures, and corresponding apparent temperatures (ATs) in the warm season (April to September) were correlated with excess total mortality in 2007, taken as the difference of daily death counts or their 7-d moving averages with those of the reference period. Observed excess mortality was totalled about 190-200 deaths or 6.5-6.9% of the reference mortality. The average daily excess deaths above the threshold temperatures (TTs), in terms of a used estimator' (a temperature variable), were in the range of 2.0-4.4% per 1 degrees C. TTs were identified as the lowest 2 degrees C class intervals above which the excess mortality rates began a sharp increase from their zero reference value. For T-mean, T-max and T-min they were estimated as approximate to 25, 31 and 19 degrees C; TTs for ATs were somewhat lower. The heat waves were defined as a continuous period satisfying three conditions for daily T-max: (1) it is above the 99th percentile of its reference distribution (2000-2008) for at least three consecutive days, (2) its average value is equal to at least this percentile for the entire period and (3) all daily values are above 90th percentile for the entire period. On the whole, eight heat events caused 146 excess deaths or about 73-77% of their total number in the warm period of 2007. Temperature-excess mortality relationships become stronger with an increasing time lag; maximal effects were revealed on the second-third days for T-mean and T-max, and on the first-seconddays for T-min. The total effect of mortality displacement was estimated as about 17-25% of positive' excess deaths.