Changes in the concentration and composition of urban aerosols during the COVID-19 lockdown

Abstract

This work investigates the impact of COVID-19 restrictive measures on the mass concentrations of PM 1 and PM 10 , and their chemical components (water-soluble ions, organic and elemental carbon, and major and trace metals) at an urban site in the western Mediterranean. The evolution of gaseous pollutants (NO x , O 3 and some volatile organic compounds) was also analyzed. The concentrations measured during the lockdown in 2020 were compared to those obtained during the same period over the preceding five years. The average decrease in the levels of NO x and traffic-related volatile organic compounds was higher than 50 %, while O 3 concentrations did not exhibit significant variations during the study period. Our results show that temporal variations in PM 1 and PM 10 concentrations were strongly affected by the frequency of Saharan dust events. When these episodes were excluded from the analysis period, a 35 % decrease in PM 1 and PM 10 levels was observed. Traffic restrictions during the lockdown led to important reductions in the concentrations of elemental carbon and metals derived from road dust (e.g. Ca and Fe) and break wear (e.g. Cu). Regarding secondary inorganic aerosols, nitrate showed the largest reductions as a consequence of the drop in local emissions of NO x .

Molecular Tracer Characterization during COVID-19 Pandemic in Shanghai: Changes in the Aerosol Aqueous Environment and Implications for Secondary Organic Aerosol Formation

“…The concentrations of OC, EC, and WSOC during DL in 2020 were lower than those during AL, while the concentrations during DL in 2019 were higher than those during AL in 2019, approving the reduction of carbonaceous aerosol due to the COVID lockdown. Significant reductions in carbonaceous aerosol during the DL stage in 2020 have also been observed in other studies. − No significant difference in the meteorological conditions, such as temperature, RH, and wind speed, between 2019 and 2020 was found, indicating that the major contributor to the difference in carbonaceous aerosol between 2019 and 2020 was the reduced anthropogenic emissions during the lockdown.…”

Insights on Air Pollution During COVID-19: A Review

“…The reduction in atmospheric pollutants concentration level has been assessed based on the estimation of criteria pollutants such as particulate matter (PM 2.5 , PM 10 ), nitrogen dioxide (NO 2 ), sulfur dioxide (SO 2 ), ozone (O 3 ), and carbon monoxide (CO) over different monitoring station (Adam et al 2021 ; Jain and Sharma 2020 ; Xu et al 2020 ). Several studies have been discussed using comparative analysis before lockdown, during the lockdown, and after a lockdown in different cities of the world (Zheng et al 2020 ; Cui et al 2020 ; Hicks et al 2021 ; Chatterjee et al 2021 ; Giardi et al 2022 ; Clemente et al 2022 ). The selection of time duration before the lockdown period or reference period varies with variation in the studies.…”

Chemical characteristics and sources of PM2.5 in Hohhot, a semi-arid city in northern China: insight from the COVID-19 lockdown

“…In addition, this scenario can be used by policymakers to formulate effective policies to prevent atmospheric pollution. Stringent traffic restrictions during the COVID-19 lockdown led to important reductions in the concentrations of elemental carbon, metals and nitrate at an urban site of the western Mediterranean (Clemente et al, 2022). The substantial reduction in nitrate in the Beijing-Tianjin-Hebei region during the LD period was attributed to the drastic reduction in vehicular movement and the suspension of public transport (Sulaymon et al, 2021).…”