Characteristics of ambient ozone (O3) pollution and health risks in Zhejiang Province.

Troposphere ozone, which is from secondary formation processes, has been increasing dramatically during the last decades in China, inducing high health risks. In this study, temporal and spatial distribution of O3 was studied among 13 sites of three cities during 2014-2016. The objectives were to clarify the characteristics of the ambient pollution of O3 under the influence from other pollutants and meteorological parameters and the health outcomes from exposure to O3. The concentrations of O3 during summer were much higher than those during winter, and the concentrations in downtown areas were higher than in rural or mountain areas. PM2.5, NO2, SO2, and wind speed (WS) were negatively correlated with O3, and CO, temperature (T), and relative humidity (RH) were positively correlated with O3. In multivariable analysis, two separate factors-solar radiation and atmospheric diffusion status, affected the O3 levels. The concentrations of O3 reached the highest level at 15:00 and the lowest value at about 6:00-8:00, with the similar trend to T and WS, and opposite to RH. According to the dose-response model, relative risks (RRs) and population attributable fractions (PAFs) with confidence intervals (CIs) for chronic obstructive pulmonary disease (COPD) from exposure to O3 were 1.0612 (CI 1.0607-1.0616) and 5.32% (CI 5.29-5.36%), respectively, attributable to 2000 deaths in Zhejiang Province in 2014.