New research reveals drivers of regionally different ozone responses to the COVID-19

February 07, 2021

The outbreak of COVID-19 raised a question about the relationship between anthropogenic emissions and air pollution, which has aroused heated discussion. Research on air-quality changes caused by the lockdowns in different areas shows similar substantial reductions in primary emissions. However, regional disparities exist in responses of secondary pollutants to emissions reduction, especially fine particulate matter and ozone (O3).

Professor Ding Aijun and his team from Nanjing University explored global air-quality changes during COVID-19 lockdowns and regional disparities in O3 responses to emission reductions. They integrated multiple observational datasets, including global air quality monitoring network and satellite retrievals, to shed more light on the regional differences in interactions between emissions, atmospheric chemistry, and meteorological conditions. Their findings were recently published in Atmospheric and Oceanic Science Letters.

"Observational signals of air-quality change were extracted from multi-year ground-based measurements and satellite-retrieved atmospheric composition columns. Ozone shows rising signals in most areas of both East Asia and Europe, whereas a non-negligible declining signal exists in North America, despite reductions in nitrogen oxides (NOx) over the three regions. This indicates significant differences in the relationships between NOx and O3 changes," says by Prof. Ding.

Furthermore, Ding and his team investigated meteorological and atmospheric chemical drivers behind the different O3 responses based on data analysis and proxy indicators (HCHO/NO2) for diagnosing O3 photochemical sensitivity. They found that the responses of O3 to declines in NOx can to a certain extent be affected by the primary dependence on its precursors. The response of O3 in Europe fits particularly well with the O3 sensitivity regimes.

The study points out that meteorological factors--especially temperature--are rather important drivers of O3 responses. Apart from weakened titration effects caused by declines in NOx, increased O3 in East Asia and Europe tended to be largely dominated by the climatologically warmer temperatures during the lockdowns in 2020.

"Still, the contribution of rising temperature may have been partly offset by weakened photochemical reactions due to a decline in solar radiation and an increase in relative humidity in southern China and southern Europe. For North America, declines in temperature and substantial increases in humidity might have been important contributors to the decreased O3 over the western coasts," concludes by Prof. Ding.

By investigating the impacts of meteorological conditions and chemical sensitivity under emission reductions, this research was able to emphasize the importance of regional disparities and combined effects of precursor reductions and meteorological influences in mitigating O3 pollution.
-end-


Institute of Atmospheric Physics, Chinese Academy of Sciences

Related Ozone Articles from Brightsurf:

Investigating the causes of the ozone levels in the Valderejo Nature Reserve
The UPV/EHU's Atmospheric Research Group (GIA) has presented a database comprising over 60 volatile organic compounds (VOC) measured continuously over the last ten years in the Valderejo Nature Reserve (Álava, Basque Country).

FSU Research: Despite less ozone pollution, not all plants benefit
Policies and new technologies have reduced emissions of precursor gases that lead to ozone air pollution, but despite those improvements, the amount of ozone that plants are taking in has not followed the same trend, according to Florida State University researchers.

Iodine may slow ozone layer recovery
Air pollution and iodine from the ocean contribute to damage of Earth's ozone layer.

Ozone threat from climate change
We know the recent extreme heat is something that we can expect more of as a result of increasing temperatures due to climate change.

Super volcanic eruptions interrupt ozone recovery
Strong volcanic eruptions, especially when a super volcano erupts, will have a strong impact on ozone, and might interrupt the ozone recovery processes.

How severe drought influences ozone pollution
From 2011 to 2015, California experienced its worst drought on record, with a parching combination of high temperatures and low precipitation.

New threat to ozone recovery
A new MIT study, published in Nature Geoscience, identifies another threat to the ozone layer's recovery: chloroform -- a colorless, sweet-smelling compound that is primarily used in the manufacturing of products such as Teflon and various refrigerants.

Ozone hole modest despite optimum conditions for ozone depletion
The ozone hole that forms in the upper atmosphere over Antarctica each September was slightly above average size in 2018, NOAA and NASA scientists reported today.

Increased UV from ozone depletion sterilizes trees
UC Berkeley paleobotanists put dwarf, bonsai pine trees in growth chambers and subjected them to up to 13 times the UV-B radiation Earth experiences today, simulating conditions that likely existed 252 million years ago during the planet's worst mass extinction.

Ozone at lower latitudes is not recovering, despite Antarctic ozone hole healing
The ozone layer -- which protects us from harmful ultraviolet radiation -- is recovering at the poles, but unexpected decreases in part of the atmosphere may be preventing recovery at lower latitudes.

Read More: Ozone News and Ozone Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.