China’s COVID-19 traffic restrictions helped ward off air pollution-related deaths

BUFFALO, N.Y. — At the start of the COVID-19 outbreak in January, China implemented strict traffic measures to limit residents’ mobility. The goal was to reduce the spread of the disease, which by that point had already affected a large portion of the country.

But the countrywide ban on traffic mobility had another effect: It significantly reduced vehicle emissions, which may have prevented a higher number of deaths that would have been attributable to air pollution than fatalities caused by the novel coronavirus, according to a comment paper published in The Lancet Planetary Health by researchers from Yale University, the University at Buffalo and Boston University.

“Our estimates suggest that interventions to contain the COVID-19 outbreak led to improvements in air quality that brought health benefits in non-COVID-19 deaths, which could potentially have outnumbered the confirmed deaths attributable to COVID-19 in China,” said paper co-author Meng Wang, PhD, an assistant professor of epidemiology and environmental health in UB’s School of Public Health and Health Professions.

An expert on air pollution in China, Wang is also affiliated with UB’s Research and Education in eNergy, Environment and Water (RENEW) Institute.

The authors defined the pre-quarantine period for China as Jan. 5-20, while the quarantine period extended from Feb. 10 through March 14. Researchers examined daily concentrations of the traffic-related air pollutants nitrogen dioxide (NO2) and particulate matter (PM) 2.5 in 367 Chinese cities between Jan. 1, 2016 and March 14, 2020. Exposure to fine particles such as PM 2.5 can affect lung function and exacerbate medical conditions.

NO2 and PM 2.5 emissions dropped substantially as a result of the traffic bans and quarantine measures. Researchers calculated changes in air quality during the quarantine and compared those with corresponding changes from 2016 to 2019.

The team reported that nitrogen dioxide levels dropped by 22.8 micrograms per cubic meter in Wuhan and 12.9 in China overall. Meanwhile, PM 2.5 dropped by 1.4 micrograms per cubic meter in Wuhan but decreased by 18.9 across 367 cities.

Researchers estimate that improved air quality during the quarantine period avoided a total of 8,911 NO2-related deaths, 65% of which would have been from cardiovascular diseases and chronic obstructive pulmonary disease, or COPD. In addition, they estimate that 3,214 PM2.5 deaths were avoided, 73% of which would have been  from cardiovascular disease and COPD.

There were 4,633 deaths in China attributable to COVID-19 as of May 4, researchers note.

“Although COVID-19 has caused increased deaths and health risks in the past several months, we found an unexpected health benefit due to the effectiveness of stricter combustion control polices, especially  travel bans,” Wang said.

“Our findings show the substantial human health benefits related to cardiovascular disease morbidity and mortality that can be achieved when aggressive control measures for air pollution are taken to reduce emissions from vehicles, such as through climate mitigation-related traffic restrictions or efforts to accelerate the transition to electric vehicles,” said Kai Chen, PhD, assistant professor at Yale School of Public Health and the study’s lead author.

“If we can address climate change as aggressively as we are fighting COVID-19 but in a sustainable and healthy way, we can prevent the enormous health burdens of climate change without having the devastating consequences of a coronavirus pandemic,” Chen added.