Acute effects of air pollution on all-cause mortality: a natural experiment from haze control measures in Chiang Mai Province, Thailand.

ABSTRACT: Background:Serious haze episodes have been a seasonal event in Chiang Mai province for more than a decade. In 2008, local government agencies introduced comprehensive measures to control haze and limit its impacts on public health. This study assessed the acute effects of ambient air pollutants on all-cause mortality before and after the introduction of those haze control measures. Methods:We obtained daily mortality counts and data on mass concentrations of particulate matter <10 micron in aerodynamic diameter (PM10), gaseous pollutants (SO2, NO2, O3, and CO), and meteorology in Chiang Mai Province between January 2002 and December 2016. We analyzed the data using a case-crossover approach adjusting for temperature, relative humidity, seasonality, and day-of-week. We assessed change in the excess risks of all-cause mortality associated with an increase in interquartile range (IQR) of pollutant concentration before and after control measures came into force. Results:We found decreased PM10 levels and markedly reduced excess risks of daily mortality associated with an IQR increase in PM10 concentrations in the years after haze-control measures were implemented (2009-2016). We found mixed results for gaseous pollutants: SO2 showed no significant change in excess risk of daily mortality throughout the study period, while NO2 and CO showed significant excess risks only in the period 2012-2016, and 8-h maximum O3 showed a decrease in excess risk despite an increase in its atmospheric levels after the introduction of haze control measures in 2008. Conclusions:The findings indicate that the government haze control measures first introduced in Chiang Mai province in 2008 have successfully reduced episodic PM10 concentrations, which has led to a decrease in short-term all-cause mortality.

SUBMITTER: Vajanapoom N 

PROVIDER: S-EPMC7261137 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature