[Association between ambient inhalable particle pollution and mortality due to circulatory disease in Nanjing: a...

To explore the short-term effects of ambient PM10 pollution on mortality due to circulatory diseases, and to study the modifying effect of season on the association between ambient PM10 concentration and mortality in Nanjing.

Daily mortality, air pollution, and meteorological data from 1 January 2009 to 31 December 2013 in Nanjing were collected; Time-stratified case-crossover design was used to analyze the associations between daily average concentration of inhalable particle (PM10) and mortality due to circulatory diseases; Odds ratios (OR) and 95% confidence intervals (CI) were calculated; And stratified analysis was conducted to compare the mortality risks of circulatory diseases exposed to outdoor PM10 in warm season (May-October) with that in cool season (November-April).

The mean daily average concentrations of PM10, NO2, and SO2 from 2009 to 2013 in Nanjing were 109.1, 51.5, and 35.4 µg/m(3), respectively. During our study period, a total of 78 299 circulatory disease deaths were recorded. On average, there were approximately 43 circulatory disease deaths per day; and deaths due to cardiac diseases, ischemic heart disease and cerebrovascular diseases were 19, 10 and 24 per day, respectively. After adjusting for the meteorological variables such as daily temperature, relative humidity and air pressure, a10 µg/m(3) increment of PM10 was associated with the mortality on values of (OR) 1.002 4 (95% CI: 1.000 1-1.004 8) for total circulatory diseases, 1.004 8 (95% CI: 1.001 3-1.008 3) for cardiac diseases, 1.007 3 (95% CI: 1.002 4-1.012 3) for ischemic heart disease and 1.000 5 (95% CI: 0.998 5-1.002 4) for cerebrovascular diseases, respectively. In summer season, the OR values of daily mortality for total circulatory diseases and cerebrovascular diseases were 1.008 0 (95% CI: 1.003 9-1.012 2) and 1.005 7 (95% CI: 1.002 0-1.009 4), respectively, the corresponding OR values in cool season were 1.001 4 (95% CI: 0.998 5-1.004 2) and 0.998 8 (95% CI: 0.996 4-1.001 2), respectively; The effect estimates in warm season were higher than that in cool season.

The elevated levels of ambient PM10 were positively associated with the increase of mortality due to circulatory diseases, and season may modify the effects of outdoor PM10 pollution on mortality.