Nitrogen dioxide levels in China ebbed after the outbreak of SARS-CoV-2, particularly after the outbreak was first announced and when lockdown measures were introduced.

view of polluting factories in chinaShare on Pinterest
New research suggests that lockdown measures helped reduce pollution in China.

All data and statistics are based on publicly available data at the time of publication. Some information may be out of date.

A silver lining of the SARS-CoV-2 pandemic has been the temporary environmental benefits that various lockdown measures have brought about.

These are likely to end as lockdown measures are eased; indeed, air pollution from traffic is likely to be worse, as people may prefer driving to using public transit. Still, lockdowns have allowed people to see the effects of significant societal changes on the environment.

A new special collection of papers in the journal Science Advances will explore the relationship between pandemics, including the ongoing COVID-19 pandemic, and the environment — emphasizing the ways that global processes are interconnected.

The special collection was commissioned by Science Advances Deputy Editors Prof. Kip Hodges, of the Arizona State University’s School of Earth and Space Exploration, and Prof. Jeremy Jackson, of the University of California, San Diego’s Scripps Institution of Oceanography.

In their editorial to the special collection, Profs. Hodges and Jackson write, “Economic lockdowns this year, designed to slow the spread of COVID-19, have been like pressing the pause button on environmental degradation, and the resulting reductions in air and water pollution are dramatic.”

“Such trends remind us of how much our actions drive environmental quality and just how badly we have behaved as stewards of our planet.”

For the team, a key question concerns the world’s response to these environmental issues following the pandemic’s resolution.

They note, “We have a once-in-a-generation opportunity to rethink how we grow back our economies in a way that does not imperil the global environment as we have in recent decades.”

They recommend: heavily investing in green energy, developing scientific methods that can account for the interconnectedness of global processes, and developing policy at a government level that responds to this scientific research.

The first paper in the special collection looks at the effects of the lockdown in China on nitrogen dioxide levels across the country.

Nitrogen dioxide is one of a number of gases that are central to air pollution. As well as being a pollutant, nitrogen dioxide also contributes to other harmful pollutants, such as ozone and particulate matter.

According to the World Health Organization (WHO), long-term exposure to nitrogen dioxide can worsen childhood bronchitis and asthma and cause reduced lung function growth.

The human-influenced sources of nitrogen dioxide are all related to combustion: vehicle engines, power generation, and heating.

As industries shut down and people stayed at home, these sources of combustion were less active. The researchers behind the study set out to analyze the effects of this response on nitrogen dioxide levels.

To do this, the researchers looked at data collected by satellites for 20 days on either side of the Lunar New Year, January 25, 2020.

The nitrogen dioxide levels were detected using the Ozone Monitoring Instrument onboard a NASA satellite and the Tropospheric Monitoring Instrument mounted on a European Space Agency satellite.

The team found significant reductions in nitrogen dioxide at two points: when the COVID-19 outbreak was first announced and when lockdown measures were implemented in response.

Nitrogen dioxide levels typically reduce around the Lunar New Year because factories shut down and there are fewer vehicles on the roads. However, this time, the reduction was around 21% greater than those between 2015 and 2019.

According to lead study author Fei Liu, Ph.D., of the Universities Space Research Association, in Columbia, MD, and her co-authors, “While temporary, these substantial reductions in air pollution may have [a] positive health impact for lives in otherwise heavily polluted areas.”

“This unusual period offers a rare counterfactual of a potential society which uses substantially less fossil fuels and has lower mobility.”

For live updates on the latest developments regarding the novel coronavirus and COVID-19, click here.