Mortality Related to Interactions between Heat Wave and Wildfire Air Pollution during the summer of 2010 in Moscow

Abstract

Background: Evidence is lacking on interactions between prolonged high temperatures and air pollution from wild fires in relation to cause-specific mortality, although these exposures often occur together. Methods: We analyzed day-to-day variations in number of deaths in relation to air pollution levels and temperature during the heat wave and wild fire smog incident in the summer of 2010 in Moscow, Russia. Corresponding data for the period 2006 to 2009 were used for comparison. Daily average levels of PM10 and ozone were obtained from several continuous measurement stations. The daily number of non-accidental deaths from specific causes was extracted from official records. Analyses of interactions considered the main effect of temperature as well as the added effect of prolonged high temperatures and focused on PM10. Results: The major heat wave lasted for 44 days with 24h average temperatures ranging from 24 to 31°C and PM10 levels exceeding 300 µg/m3 on several days. There were close to 11,000 excess deaths from non-accidental causes during this period, mainly among those over 65 years, but increased risks occurred also in younger age groups. The most pronounced effects were observed for deaths from cardiovascular, respiratory, genitourinary and nervous system diseases. Continuously increasing risks following prolonged high temperatures were apparent during the first two weeks of the heat wave. Interactions between high temperatures and air pollution from wild fires contributed to more than 2,000 deaths. Conclusions: Interactions between high temperatures and wild fire air pollution should be considered in the risk assessment regarding health consequences of climate change.