Ambient air pollution ranks high among the risk factors that increase the global burden of disease. Previous studies focused on assessing mortality risk and were sparsely performed in populous developing countries with deteriorating environments. We conducted a time-series study to evaluate the air pollution-associated years of life lost (YLL) and mortality risk and to identify potential modifiers relating to the season and demographic characteristics. Using linear (for YLL) and Poisson (for mortality) regression models and controlling for time-varying factors, we found that an interquartile range (IQR) increase in a three-day average cumulative (lag 0-2 day) concentrations of PM2.5, PM10, NO2 and SO2 corresponded to increases in YLL of 12.09 (95% confidence interval [CI]: 2.98-21.20), 13.69 (95% CI: 3.32-24.07), 26.95 (95% CI: 13.99-39.91) and 24.39 (95% CI: 8.62-40.15) years, respectively, and to percent increases in mortality of 1.34% (95% CI: 0.67-2.01%), 1.56% (95% CI: 0.80-2.33%), 3.36% (95% CI: 2.39-4.33%) and 2.39% (95% CI: 1.24-3.55%), respectively. Among the specific causes of death, cardiovascular and respiratory diseases were positively associated with gaseous pollutants (NO2 and SO2), and diabetes was positively correlated with NO2 (in terms of the mortality risk). The effects of air pollutants were more pronounced in the cool season than in the warm season. The elderly (>65 years) and females were more vulnerable to air pollution. Studying effect estimates and their modifications by using YLL to detect premature death should support implementing health risk assessments, identifying susceptible groups and guiding policy-making and resource allocation according to specific local conditions.
Keywords: Air pollution; Modifiers; Non-accidental mortality; Time-series study; Years of life lost.
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