HEAT-WAVES IN METROPOLISES AND THRESHOLDS OF THEIR IMPACT ON PUBLIC HEALTH
Heat waves have become an important health risk factor in megalopolises. Threshold temperatures for heat wave identification have been analyzed and heat wave impacts on the mortality rate in cities of different climatic zones have been compared. Relative increases in the mortality rate per each increase in the temperature by 10С in daily mean temperatures above the heat thresholds in European cities with moderate climate varied between 1.1% and 3.7% while those indices in cities with subtropical monsoon climate varied between 2.8% and 3.0%. Heat waves in cities with moderately continental climate led to greater gains in the all-causes mortality rate than heat waves in cities with other types of climate. Relative gains in the mortality rate were greater among the elderly persons. This paper provides a rationale for the using heat wave thresholds as new hygienic standard of environmental quality in cities. The authors proposed to use the 98th percentile of long-term historic distribution of daily mean temperatures as an identifier of dangerous for health heat waves. The authors recommend use this heat threshold for the activation of appropriate preventive measures to avoid heat-related deaths among urban population.