Changes of air pollutants and simulation of a heavy pollution process during COVID-19 in Shenyang

Abstract

During COVID-19, Shenyang implemented strict household isolation measures, resulting in a sharp reduction in anthropogenic emission sources, providing an opportunity to explore the impact of human activities on air pollution. The period from January to April of 2020 was divided into normal period, blockade period and resumption period. Combined with meteorological and pollutant data, mathematical statistics and spatial analysis methods were used to compare with the same period of 2015–2019. The results showed that PM 2.5 , PM 10 , NO 2 and O 3 increased by 32.6%, 13.2%, 4.65% and 22.7% in the normal period, among which the western area changed significantly. During the blockade period, the concentration of pollutants decreased by 35.79%, 35.87%, 32.45% and -4.84%, of which the central area changed significantly. During the resumption period, the concentration of pollutants increased by 21.8%, 8.7%, 5.7% and -6.3%, and the area with the largest change was located in the western. During the blockade period, a heavy pollution occurred with PM 2.5 as the main pollutant. The WRF-Chem model and the HYSPLIT model were used to reproduce the pollution occurrence process. The result showed that winds circulated as zonal winds during the pollution process at high altitudes. These winds were controlled by straight westerly and weak northwesterly airflows in front of the high pressure, and the ground was located behind the warm low pressure. Weather conditions were relatively stable. Thus, high temperatures (average > 10 ℃), high humidity (40%-60%) and slow wind (2 m/s) conditions prevailed for a long time in the Shenyang area. The unfavorable meteorological conditions lead to the occurrence of pollution. The backward trajectory showed that the potential source areas were concentrated in the urban agglomeration around Shenyang, and sporadic contributions came from North Korea.

The Influence of Meteorological Factors on the Effect of SARS-CoV-2 Transmission and Its Delayed Effect

“…This paper uses the rate of same-day infection as the response variable. A study published by the European CDC in September 2022 showed that antibody protection dropped to 51% three months after infection with Omicron and 25% six months later [10]. This paper sets up a simple linear function (proportion of those infected-on a given day in history whose antibodies failed on today = 0.25 + number of days from today * 5 / 18000) based on this data, which is used to calibrate the infection rate to some extent.…”

“…The study by Choi and Kim et al established a 2-day delay, but did not elaborate [3]. The study by Ma et al established a delay interval of 1 to 5 days, but the interval was clearly too small [1]. Therefore, this paper also deals with an in-depth study of the delayed effect of meteorological factors on the effect of new coronavirus transmission.…”

“…There is a wide range of studies on the effect of temperature and humidity on the spread of the new crown virus. An analysis of Wuhan COVID-19 epidemic data at the beginning of the new crown epidemic in 2020 by Ma et al concluded that diurnal temperature difference was positively associated with the number of deaths and relative humidity was negatively associated with the number of deaths [1]. Nottmeyer et al used data from 455 cities in 20 countries, a negative correlation was analysed between temperature and absolute humidity and the effect of new coronavirus transmission [2].…”

Bangkok port and coastal regions of Thailand under atmospheric PM2.5 pollution: A hypothetical nuclear power plant accident

“…In addition to emission sources, weather conducive to the accumulation of pollution is another reason to consider. Adverse weather conditions are considered one of the main reasons for Southeast Asia and Thailand's severe air pollution in recent years, as can be seen from many researchers who studied meteorological factors during air pollution (Amnuaylojaroen et al, 2020;Bran et al, 2022;Chao & Min, 2021;Liu et al, 2020;Ma et al, 2022;Qi et al, 2021;Wang & Li, 2022). These researchers found that most air pollution and meteorological factors have prominent seasonal and regional characteristics.…”