Mortality related to air pollution with the moscow heat wave and wildfire of 2010

Abstract

Background: Prolonged high temperatures and air pollution from wildfires often occur together, and the two may interact in their effects on mortality. However, there are few data on such possible interactions.

Methods: We analyzed day-to-day variations in the number of deaths in Moscow, Russia, in relation to air pollution levels and temperature during the disastrous heat wave and wildfire of 2010. Corresponding data for the period 2006-2009 were used for comparison. Daily average levels of PM10 and ozone were obtained from several continuous measurement stations. The daily number of nonaccidental 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 the interaction with PM10.

Results: The major heat wave lasted for 44 days, with 24-hour average temperatures ranging from 24°C to 31°C and PM10 levels exceeding 300 μg/m on several days. There were close to 11,000 excess deaths from nonaccidental causes during this period, mainly among those older than 65 years. Increased risks also occurred in younger age groups. The most pronounced effects were for deaths from cardiovascular, respiratory, genitourinary, and nervous system diseases. Continuously increasing risks following prolonged high temperatures were apparent during the first 2 weeks of the heat wave. Interactions between high temperatures and air pollution from wildfires in excess of an additive effect contributed to more than 2000 deaths.

Conclusions: Interactions between high temperatures and wildfire air pollution should be considered in risk assessments regarding health consequences of climate change.

FIGURE 1.

Daily nonaccidental deaths, mean temperature, and PM₁₀ levels in Moscow during the summer of 2010. Solid lines show observed values; dashed lines, expected values.

FIGURE 2.

Relative increase in nonaccidental mortality 2006–2010 in Moscow related to temperature, averaged over 1 week, compared with a temperature of 18°C. The graphs indicate mean relative increase and 95% confidence interval.

FIGURE 3.

Relative increase in nonaccidental mortality in Moscow between 6 July and 18 August 2010 attributable to the effect of consecutive heat wave days. The graphs indicate mean relative increase and 95% confidence interval.

FIGURE 4.

Estimated contributions from temperature, air pollution, and their interaction to daily number of nonaccidental deaths in Moscow during the heat wave period in the summer of 2010. “Interaction” is between PM₁₀ and temperature; “pollution” is PM₁₀ and ozone; “added” is the heat wave effect in addition to the temperature effect; and “main” is the temperature effect.