Observations on the Particle Pollution of the Cities in China in the COVID-19 Closure: Characteristics and Lesson for Environmental Management

ABSTRACT

Abstract Particulate matter in the air seriously affects human health and has been a hot topic being discussed. Because of the COVID-19 lockdown of the cities in China, sources of the particulate matter including gasoline burning vehicles, dust producing building sites, coal-fired factories, almost all stopped working since the end of January 2020. It was not until early April that outdoor activities recovered. Ten cities were selected as the observation sites in the period from 12/19/2019 to 04/30/2020, covering the periods of the pre-closure, the closure and the gradual resumption. 11720 groups of data were obtained and four indicators were applied to assess the characteristics of the particle pollution in the period. The quality of the atmospheric environment was visually influenced by human activities in the four months. The PM10 concentrations decreased slightly in February and March, and then began to increase gradually after April with the gradual recovery of production. The concentrations of PM2.5 reduced greatly in most regions especially in northern cities, during the closure and maintained a relatively stable level in the following three months. The trends of PM10 and PM2.5 indicated that the reduced human activities during the COVID-19 lockdown made the concentrations of the particulate matter in the air decreased, and the difference between the PM10 and PM2.5 trends might be due to the different sources of the two particles and their different aerodynamics. However, during the closure, the pollution of the particulate matter in the cities still remained at a high level, which indicated that some ignored factors except the outdoor production activities, automobile exhaust and sites? dust might have been contributing much to the PM10 and PM2.5 concentrations, and the traceability of the particulate matter should be paid further attention in environmental management. This article is protected by copyright. All rights reserved.