Analysis of ozone pollution causes under influence of extreme high temperatures and power rationing measures: Chengdu, China

Abstract

Ozone(O3) pollution has become increasingly severe and persistent in recent years. A persistent O3 pollution event occurred in Chengdu in 2022 during a period of extreme high-temperature weather. In response, the government implemented power rationing measures to restrict industrial electricity consumption. Based on the observational data, an observation based model (OBM) and probability mass function (PMF) are used to study the effect of power rationing on the O3 formation mechanism. After power rationing, the temperature increased by 1.7 °C,despite the conditions for O3 generation were more favorable, the O3 concentration was reduced. This is mainly because the power rationing measures reduced non-methane hydrocarbons (NMHCs) by about 22.71 % and reduced the generation of organic peroxide radicals (RO2), thereby suppressing O3 generation. The reduced NMHCs primarily came from solvent use sources. In recent years, extreme high-temperature days have occurred frequently, and the O3 pollution situation has become grim. This study seeks to understand the influence of human activities on O3 in Chengdu under extreme high-temperature conditions, emphasizes that O3 pollution prevention and control measures in Chengdu should consider addressing solvent use sources, reducing the NMHC, and the adopting of regional joint preventive and control measures, and provides references for other regions.