The Interactions Of Ambient PM₁₀, NO₂ And O₃ On Mortality In Guangzhou

Objective This study aims to estimate the interactions between each two ambient air pollutants of particles with an aerodynamic diameter less than 10μm(PM10), nitrogen dioxide(NO2) and ozone(O3) on mortality in Guangzhou City, Guangdong Province, China. Method Time series data from 2006 to 2010 on mortality, as well as concentrations of ambient air pollutants(PM10, NO2 and O3) in Guangzhou were collected. Generalized additive model was built to examine the excessive relative risk(ERR) of single pollutant on mortality in different lag time. Then used two interaction models(two variables model and stratified model) to explore the possible interactions between each two of PM10, NO2 and O3. Results There seemed greater risks for total-non-accidental death and cardiovascular deaths when concentrations of PM10 and NO2 both increased. Furthermore, effects of PM10 [ERR%: 0.46%(95%CI: 0.13%, 0.79%), ERR%: 0.61%(95%CI: 0.06%, 1.16%)] were greatest on the days with high NO2 level(greater than 75 th percentile of distribution), and vice versa [ERR%: 0.92%(95%CI: 0.42%, 1.42%), ERR%: 1.20%(95%CI: 0.38%, 2.03%]. Similar interactions could be observed between NO2 and O3. A 10μg/m3 increase of lag 0-2 NO2 and O3 was associated with an increase of 1.38%(95%CI: 0.66%, 2.10%) and 2.03%(95%CI: 0.96%, 3.11%) for total-non-accidental deaths, and 1.98%(95%CI: 0.80%, 3.18%) and 2.30%(95%CI: 0.52%, 4.11%) for cardiovascular deaths when the other one was at high level(greater than 75 th percentile of distribution). PM10 and O3 induced greater risks for total-non-accidental deaths when they increased simultaneously. The effects of PM10 [ERR%: 1.00%(95%CI: 0.50%, 1.51%)] were greatest when O3 at high level(greater than 75 th percentile of distribution), and vice versa [ERR%: 1.42%(95%CI: 0.43%, 2.43%)]. Conclusion Interactions between each two pollutants of ambient PM10, NO2 and O3 could raise the risks of non-accidental deaths at lag 0-2 days in Guangzhou. Mortality of cardiovascular diseases also increased due to interactions of PM10 and NO2, NO2 and O3.