Category: COVID-19 and Air Pollution: A Double Whammy

Thomas Bourdrel et al. (2021) published a paper during the height of the COVID-19 pandemic reflecting on the role of air pollutants in spreading the COVID-19 virus. 

Their central thesis argues that a double-faceted mechanism — the initial responses of our bodies to the dirty air environment, and air particulates as vectors — contribute to the spread of COVID-19. They argue that PM and gaseous pollutants may decrease immune responses as evident by increased mucus production and difficulty breathing. Fine particles may also serve as vectors for other airborne viruses, provided the exposure to heat and UV radiation has not denatured the viral proteins. Short term and long term exposures to the natural environment may thus open up individuals to the virus.

Air pollutants/virus interaction according to atmospheric conditions (Bourdrel et al., 2021)

Indeed, pollutants were significantly reduced when lockdowns, travel restrictions and fear of the unknown deterred people from venturing beyond their neighbourhoods. The decrease in air pollutants could have played a role in reducing the spread of the more deadly SARS-COV-2 Alpha variant. 

However, now that vaccines and less deadly variants have emerged, air pollution is also increasing in tandem with increased mobility. It could therefore be argued that the high infection rate of the Delta and Omicron variants are in part perpetuated by increased air pollutant particles.

This could explain the resurgence of Delta and Omicron variants in China where the air quality has deteriorated post-lockdown. Heavily polluted Shanghai is now considering an additional lockdown at the time of this writing. 

As Bourdrel et al. (2021) argues, “We cannot ignore that our surrounding environment may be exacerbating not only chronic disease, but infectious disease as well”. Industries polluting the air not only increase the difficulty of breathing directly, but also the increased vulnerability to COVID-19 may induce further difficulties for bodies unable to develop a strong response. 

Is this evidence for a COVID-19 X Air Pollution double whammy? I think so. 

It is expected by now that COVID-19 and the lockdowns have drastically decreased pollution levels in countries imposing them. The relationship between human activities and decreased primary pollution has been established.

However, a notable study by Huang et. al (2021) seemed to have differing views. The study raised questions and challenged this relationship after noting that despite generally decreasing levels of primary pollution, there were still several periods of heavy haze pollution in the Eastern part of China. 

It was then revealed that the haze was caused by secondary sources of pollution. 

Notably, a relationship was derived that due to the large decrease in nitrogen oxides from reduced transportation emissions, the ozone and nighttime nitrogen oxide radically formed. To simply the science, this increase in atmospheric oxidising capacity actually facilitated the formation of secondary particulate matter, contributing to further air pollution.

 

 

Essentially, the secondary particulate formation offsets the reduction in primary pollution caused from reduced human activity. This would completely negate the initial sentiments the the lockdown was a blessing in disguise. 

In China, haze and ozone pollution are two of the main air quality challenges that the country faces. It affects dozens of millions of lives and their health and livelihood.

Indeed, while it seems that COVID-19 was a step towards cleaner air; it could in fact turn out to be a double whammy.