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Long-Term Exposure to Urban Air Pollutants Linked to COVID-19 Mortality

As the COVID-19 pandemic continues to persist, over 200,000 people have lost their lives in the United States, and both the public health system and economy have been affected significantly.

Researchers from Emory University found that long-term exposure to urban air pollutants, especially NO2, may enhance population susceptibility to severe COVID-19 death outcomes in the US. Image Credit: The Innovation.

In a study reported in The Innovation journal on September 21st, 2020, Emory University scientists have discovered that the high mortality due to COVID-19 may be associated with long-term exposure to urban air pollution.

Both long-term and short-term exposure to air pollution has been associated with direct and indirect systemic impact on the human body by enhancing oxidative stress, acute inflammation, and respiratory infection risk.

Donghai Liang, Study Co-First Author, Emory University

Liang was joined by Liuhua Shi on this latest study.

The team investigated major urban air pollutants, such as ozone (O3), nitrogen dioxide (NO2), and fine particle matter (PM2.5) across 3,122 U.S. counties from January to July 2020.

To study the relationship between the severity of COVID-19 outcomes and ambient air pollutants, they examined two major death outcomes—the mortality rate (that is, number of COVID-19 deaths in the population) and the case-fatality rate (that is, number of deaths among the individuals diagnosed with COVID-19).

Both these indicators can provide data on the severity of COVID-19 deaths in the general population and indicate the biological susceptibility to COVID-19-related deaths, respectively.

Among the pollutants examined, NO2 was found to have the most powerful independent correlation with an increase in an individual’s susceptibility to COVID-19-related death. A 4.6 parts per billion (ppb) increase of atmospheric NO2 was linked to 11.3% and 16.2% increase in both case-fatality and mortality rate from COVID-19, respectively.

Fu Liang and his collaborators also found that even a 4.6 ppb decrease in long-term exposure to NO2 would have averted 14,672 deaths among people who tested positive for the virus.

The researchers also noted a marginally significant connection between COVID case-fatality rate and PM2.5 exposure but found no important associations with O3.

Long-term exposure to urban air pollution, especially nitrogen dioxide, might enhance populations' susceptibility to severe COVID-19 death outcomes. It's essential to deliver this message to public health practitioners and policymakers in order for them to consider protecting vulnerable populations that lived in historically high NO2 pollution including the metropolitan areas in the state of New York, New Jersey, California, and Arizona.

Donghai Liang, Study Co-First Author, Emory University

Liang also observed that air pollution is a health equity problem: the burden of NO2 pollution is not uniformly shared. People of color and those with low income generally experience higher exposure to ambient air pollution and are likely to experience a more considerable effect from the pollutants. With limited options in residency, a majority of the people live by industrial sites or highways, which make them particularly susceptible to air pollution.

The continuations and expansions of current efforts to lower traffic emissions and ambient air pollution might be an important component of reducing the population-level risk of COVID-19 case-fatality and mortality in the United States.

Donghai Liang, Study Co-First Author, Emory University

The study was financially supported by the Emory HERCULES Exposome Research Center via the National Institute of Environmental Health Sciences. Additional funding was offered by the National Science Foundation.

Journal Reference:

Liang, D., et al. (2020) Urban Air Pollution May Enhance COVID-19 Case-Fatality and Mortality Rates in the United States. The Innovation.


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