[Effects of Interaction between PM2.5 and O ₃ 8-h max on Mortality of Cardiovascular Diseases in Chengdu]

To explore the health risks of the interactive effects between PM2.5 and ozone on cardiovascular mortality in Chengdu.

Daily data on the mortality of cardiovascular diseases, including data for both men and women, during 2014-2016 were collected. The meteorological data, the daily average of particulate matter with aerodynamic diameter less than 2.5 micrometers (PM2.5), and the daily ozone 8 h maximum concentration (O ₃ 8-h max) in Chengdu of the same period were also collected. Generalized Additive Models (GAMs) were adopted to explore the respective adverse health effects of PM2.5 and O ₃ 8-h max and the synergistic effects between PM2.5 and O ₃ 8-h max on the mortality of cardiovascular diseases in the city.

The highest health risks of PM2.5 and O ₃ 8-h max for mortality of cardiovascular diseases were found to be the strongest for the cumulative effect of the lag of one day (lag01). For every 10 µg/m ³ increment in the mass concentration of PM2.5 (lag01), the associated increase in risks for total, male, and female cardiovascular mortalities was 0.35%, 0.26% and 0.38%, respectively. For every 10 µg/m ³ increment in the mass concentration of O ₃ 8-h max (lag01), the associated increase in risks for total, male, and female cardiovascular mortalities was 0.66%, 0.43%, and 1.05%, respectively. The total, male, and female cardiovascular mortalities all reached their maximum values when high concentration of PM2.5 coexisted with high concentrations of O ₃ 8-h max.

There was a synergistic amplification effect between high concentrations of PM2.5 and high concentrations of O ₃ 8-h max on cardiovascular mortality.