Springtime warming and biomass burning causing ozone episodes in South and Southwest China

Abstract

A detailed analysis of springtime ozone outbreaks in South/Southwest China is presented in this paper, providing an insight into a regional photochemical and climate problem. A major ozone episode in 2013 was the first ever in April and the worst in Hong Kong up to 2018, measuring a peak ozone concentration of 293 μg m −3. This multi-day, ozone pollution was evidenced by similar conditions in the Pearl River Delta (PRD), and an even more severe episode in Kunming (Yunnan) in Southwest China. Concurrently, widespread air temperature composite anomalies of up to about + 4°K were observed in the region, particularly during 6Z (14:00 local time). The global annual geopotential height anomaly implied increased atmospheric stability and inhibited dispersion-consistent with global warming impacts for the region. Backward trajectories, satellite observations, and transport model simulations characterized the biomass burning sources. Results indicated that activities in Indochina, South and Southwest China, and Africa were the main sources in South China while those in Burma dominated Southwest China. The close succession of outbreaks from west to east (Kunming, Guangzhou, and Hong Kong) suggests an eastward transport of ozone and precursors.

Association between ozone exposure and prevalence of mumps: a time-series study in a Megacity of Southwest China

“…With respect to the lag effects, we first constructed a single-day lag model, which however, might suffer the problem of temporal misalignment (Zhu et al 2019). As cumulative exposure had a greater impact on human health (Lee et al 2019;Samoli et al 2013), we calculated the effect between cumulative O 3 exposure and the risk of mumps based on the single-day lag model. Considering the potential impact of meteorological factors on the prevalence of mumps, we modeled the meteorological factors as confounding variables with natural cubic spline functions.…”

“…We observed that the prevalence of mumps was the highest in summer, followed by winter. The O 3 concentrations showed a During the study period, the high levels of O 3 were due to photochemical reactions and elevated concentrations of volatile organic compounds (VOCs) and NO x from industrial and transport emissions (Lee et al 2019;Su et al 2018). A plenty of previous studies have estimated the association between air pollution and respiratory infectious diseases.…”