Air Pollution, Climate Change and COVID-19

by | Feb 8, 2021

President Biden, in his January 27, 2021 speech on combating climate change, stated “Multiple studies have shown that air pollution is associated with an increased risk of death from COVID-19.” The president presented his climate change plan as a course of action that will not only reduce global warming, but also create jobs and clean up the air. While we all hope the COVID-19 pandemic will be over before President Biden’s climate change plan has an impact, COVID-19 wasn’t the first respiratory viral pandemic and it is unlikely to be the last. By reducing air pollution, we can save both current and future lives.

Air pollution increases the incidence of respiratory and cardiovascular comorbidities (Brook et al., 2010; Kelly and Fussell, 2015; Thurston et al., 2017) that increase the risk of hospitalization and/or death from COVID. Before a single study was performed on COVID and air pollution, we had every reason to believe that air pollution would be a factor affecting SARS-CoV-2 infection.

For five days in 1952, the Great Smog of London ended the life of an estimated 12,000 people, in many cases from pneumonia. Research has demonstrated a causal link between air pollution and an increased susceptibility to respiratory infections (Domingo and Rovira, 2020; Thurston et al., 2017; Woodby et al. 2020).

Air pollution causes chronic inflammation which impacts our ability to fight the virus. Ongoing research is delineating the mechanisms by which air pollution impairs the ability of the lungs to fight off infection, focusing on the specific effects of air pollution on various components of our immune system (Woodby et al, 2020). 

Early on in the pandemic, reports showed that areas of Italy, China, and the US with high levels of air pollution also had a high incidence of COVID and high hospital admissions due to COVID (Fattorini et al, 2020; Frontera et al., 2020; Zhu et al, 2020; Wu et al., 2020). A more recent report has taken into account population density and the age distribution of the populations, and still, the association of COVID with air pollution remains (Fisca et al, 2020).

The strongest evidence for a specific link between COVID and air pollution will be found when data on individuals, not just population-wide data, are obtained. Individual data will allow other risk factors such as preexisting conditions, age, smoking, and gender to be adjusted for. Unfortunately, these types of studies take time. 

One of the widely accepted guidelines for assessing causality is that there be a plausible mechanism by which a condition could cause a disorder. In the case of air pollution and COVID, there are many possible mechanisms that are currently being explored, and it is likely that we will find that air pollution increases COVID morbidity and mortality by a combination of ways (Wang et al., 2020; Woodby et al, 2020 ).

One of these hypothesized mechanisms concerns the ACE-2 receptor (Borro et al, 2020). All viruses consist of either DNA or RNA (but not both) and protein, and some viruses like SARS-CoV-2, are enclosed by an outer envelope. Unlike bacteria, viruses are not cells and must rely on a host cell to reproduce. In order for the SARS-CoV-2 virus to enter the host cell, its S protein must first bind with the ACE-2 receptor (a protein) embedded in the cell membrane. Cell membranes control what enters and leaves the cell. Air pollution has been shown to increase synthesis of ACE-2 receptors (Lin et al., 2018). Therefore, air pollution causes more proteins to be produced that would usher the virus into our cells, potentially increasing the likelihood of infection.

We all had a glimpse of what the world would be like with less pollution when traffic and industry took a brief hiatus last spring. The clear air allowed us to see beautiful vistas in India and Los Angeles long covered up by polluted air. We need to support every effort our president and government make to clean up our air, so as to reduce climate change, create jobs, improve our health, and last but not least, to lessen the impact of the next pandemic.

References

Borro M et al. (2020). Evidence-based considerations exploring relations between SARS-CoV-2 pandemic and air pollution: involvement of PM2.5 mediated up-regulation of the viral receptor ACE-2. Int J of Environ Res Public Health. 17:5573.

Brook RD et al. (2010). Particulate matter air pollution and cardiovascular disease: an update to the Scientific Statement from the American Heart Association. Circulation. 121:2331-2378.

Domingo JL, Rovira J. (2020). Effects of air pollutants on the transmission and severity of respiratory viral infections. Environmental Research. 187: 109650.

Fattorini D, Regoli F. (2020). Role of chronic air pollution levels in the COVID-19 outbreak risk in Italy. Environ Pollution. 264: 114732.

Fiasca F et al. (2020). Associations between COVID-19 incidence rates and the exposure to PM 2.5 and NO2: a nationwide observational study in Italy. Int J of Environ Res Public Health. 17(24): 9318.

Frontera A. et al. (2020). Severe air pollution links to higher mortality in COVID-19 patients: the “double-hit” hypothesis. J Infection. 81:255-259.

Kelly FJ, Fussell JC. (2015). Air pollution and public health: emerging hazards and improved understanding of risk. Environ Geochem Health. 37(4): 631-649.

Lin C, Tsai C, Sun Y, Hsieh W, Lin Y, Chen C, Lin C. (2018). Instillation of particulate matter 2.5 induced acute lung injury and attenuated the injury recover in ACE2 knockout mice. Int J Bio Sci. 14(3): 253-265.

Thurston GD et al. (2017). A joint ERS/ATS policy statement: what constitutes a adverse health effect of air pollution? An analytical framework. Eur Respir J. 49(1): 1600419.

Wang B, Chen H, Chan YL, Oliver BG. (2020). Is there an association between the level of ambient air pollution and COVID? Am J Physiol Lung Cell Mol Physiol. 319: L416-L42.

Woodby B, Arnold MM, Valacchi G. (2020). SARS-CoV-2 infection, COVID-19 pathogenesis, and exposure to air pollution: What is the connection? Ann NY Acad Sci. (Epub ahead of print).

Wu X, Nethery RC, Saath MB, Braun D, Dominici F. (2020). Air pollution and COVID-19 mortality in the United States: strengths and limitations of an ecological regression analysis. Sci Adv. 6: eabd4049.

Zhu Y, Xie J, Huang F, Caio L. (2020). Association between short-term exposure to air pollution and COVID-19: evidence from China. Sci Total Environ. 727: 138704.

About Marion Fintel, PhD
Marion Fintel retired from Talladega College as an associate professor of biology in July of 2019. During her career, she taught anatomy and physiology, as well as other biology courses, to college students for close to thirty years. Dr. Fintel earned her doctorate in physiology from LSU Health Sciences Center in New Orleans in 1982. She then received further research training as a postdoctoral scholar in the UCLA Department of Physiology. In 2013, Dr. Fintel earned a masters of science degree in public health (MSPH) in the field of epidemiology from UAB.
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