Characteristic changes of ozone and its precursors in London during COVID-19 lockdown and the ozone surge reason analysis

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Abstract

The London COVID-19 lockdown reduced emissions from anthropogenic sources, providing unique conditions for air contamination research. This research uses tropospheric ozone (O ₃), volatile organic compounds (VOCs) and NOx (NO+NO ₂) hourly monitoring data at the London Marylebone Road station from 2001 to 2020 to investigate the effects of lockdown on (O ₃) and its precursors. Both NOx and VOCs pollution showed a decreasing trend between 2001 and 2021, with a gradual increase in O ₃ in contrast. During the COVID-19 lockdown period (from 23rd March to July 4, 2020), there was a surge in O ₃ concentration, accompanied by a sharp reduction in NOx concentrations. Because all the monitoring VOCs/NOx results were less than eight during the lockdown, indicating that O ₃ formation in urban London was in the VOC-limited regime. The rapid increase in O ₃ concentrations caused by the lockdown was closely related to the rapid decrease in NOx emissions.

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Amplified ozone pollution in cities during the COVID-19 lockdown

Pierre Sicard, Alessandra De Marco, Evgenios Agathokleous … (2020)

The effect of lockdown due to coronavirus disease (COVID-19) pandemic on air pollution in four Southern European cities (Nice, Rome, Valencia and Turin) and Wuhan (China) was quantified, with a focus on ozone (O3). Compared to the same period in 2017–2019, the daily O3 mean concentrations increased at urban stations by 24% in Nice, 14% in Rome, 27% in Turin, 2.4% in Valencia and 36% in Wuhan during the lockdown in 2020. This increase in O3 concentrations is mainly explained by an unprecedented reduction in NOx emissions leading to a lower O3 titration by NO. Strong reductions in NO2 mean concentrations were observed in all European cities, ~53% at urban stations, comparable to Wuhan (57%), and ~65% at traffic stations. NO declined even further, ~63% at urban stations and ~78% at traffic stations in Europe. Reductions in PM2.5 and PM10 at urban stations were overall much smaller both in magnitude and relative change in Europe (~8%) than in Wuhan (~42%). The PM reductions due to limiting transportation and fuel combustion in institutional and commercial buildings were partly offset by increases of PM emissions from the activities at home in some of the cities. The NOx concentrations during the lockdown were on average 49% lower than those at weekends of the previous years in all cities. The lockdown effect on O3 production was ~10% higher than the weekend effect in Southern Europe and 38% higher in Wuhan, while for PM the lockdown had the same effect as weekends in Southern Europe (~6% of difference). This study highlights the challenge of reducing the formation of secondary pollutants such as O3 even with strict measures to control primary pollutant emissions. These results are relevant for designing abatement policies of urban pollution.

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Unexpected air pollution with marked emission reductions during the COVID-19 outbreak in China

Tianhao Le, Yuan Wang, Lang Xia Liu … (2020)

The absence of motor vehicle traffic and suspended manufacturing during the COVID-19 pandemic in China produced a unique experiment to assess the efficiency of air pollution mitigation. Up to 90% reduction of certain emissions during the city-lockdown period can be identified from satellite and ground-based observations. Unexpectedly, extreme particulate matter levels simultaneously occurred in northern China. Our synergistic observation analyses and model simulations show that anomalously high humidity promoted aerosol heterogeneous chemistry, along with stagnant airflow and uninterrupted emissions from power plants and petrochemical facilities, contributing to severe haze formation. Also, because of non-linear production chemistry and titration of ozone in winter, reduced nitrogen oxides resulted in ozone enhancement in urban areas, further increasing the atmospheric oxidizing capacity and facilitating secondary aerosol formation.

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The impact of COVID-19 partial lockdown on the air quality of the city of Rio de Janeiro, Brazil

Guilherme A. Dantas, Bruno Siciliano, Bruno França … (2020)

The first COVID-19 case in Brazil was confirmed on February 25, 2020. On March 16, the state's governor declared public health emergency in the city of Rio de Janeiro and partial lockdown measures came into force a week later. The main goal of this work is to discuss the impact of the measures on the air quality of the city by comparing the particulate matter, carbon monoxide, nitrogen dioxide and ozone concentrations determined during the partial lockdown with values obtained in the same period of 2019 and also with the weeks prior to the virus outbreak. Concentrations varied with substantial differences among pollutants and also among the three studied monitoring stations. CO levels showed the most significant reductions (30.3–48.5%) since they were related to light-duty vehicular emissions. NO2 also showed reductions while PM10 levels were only reduced in the first lockdown week. In April, an increase in vehicular flux and movement of people was observed mainly as a consequence of the lack of consensus about the importance and need of social distancing and lockdown. Ozone concentrations increased probably due to the decrease in nitrogen oxides level. When comparing with the same period of 2019, NO2 and CO median values were 24.1–32.9 and 37.0–43.6% lower. Meteorological interferences, mainly the transport of pollutants from the industrial areas might have also impacted the results.

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Author and article information

Journal

Journal ID (nlm-ta): Atmos Environ (1994)

Journal ID (iso-abbrev): Atmos Environ (1994)

Title: Atmospheric Environment (Oxford, England : 1994)

Publisher: Elsevier Ltd.

ISSN (Print): 1352-2310

ISSN (Electronic): 1352-2310

Publication date PMC-release: 4 February 2022

Publication date (Print): 15 March 2022

Publication date (Electronic): 4 February 2022

Volume: 273

Page: 118980

Affiliations

[a ]School of Geosciences, The University of Edinburgh, Edinburgh, EH9 3FF, United Kingdom

[b ]College of Urban and Environmental Sciences, Northwest University, Xi'an, Shaanxi Province, 710127, China

Author notes

[∗ ]Corresponding author. School of Geosciences, The University of Edinburgh, Edinburgh, EH9 3FF, United Kingdom.

Article

Publisher Item ID: S1352-2310(22)00045-0 Publisher ID: 118980

DOI: 10.1016/j.atmosenv.2022.118980

PMC ID: 8815197

PubMed ID: 35136378

SO-VID: c1f6571c-279d-4511-8752-79150e9ca158

License:

Since January 2020 Elsevier has created a COVID-19 resource centre with free information in English and Mandarin on the novel coronavirus COVID-19. The COVID-19 resource centre is hosted on Elsevier Connect, the company's public news and information website. Elsevier hereby grants permission to make all its COVID-19-related research that is available on the COVID-19 resource centre - including this research content - immediately available in PubMed Central and other publicly funded repositories, such as the WHO COVID database with rights for unrestricted research re-use and analyses in any form or by any means with acknowledgement of the original source. These permissions are granted for free by Elsevier for as long as the COVID-19 resource centre remains active.

History

Date received : 4 November 2021

Date revision received : 25 January 2022

Date accepted : 27 January 2022

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