Public health is at risk from irpollution. Irpollution has been shown to be associated with higher rates for stroke, heart disease and other illnesses. Recent research has also shown that it can lead to adverse outcomes for COVID-19.
The study, published by the Canadian Medical Association JournalThe researchers examined data on approximately 151,000 Canadians who had tested positive to COVID-19 in Ontario. They calculated their air pollution exposure by looking at addresses in five years preceding the outbreak and then assessing air pollution levels in their area. It’s an imperfect metric, the study authors acknowledge; individuals’ pollutant exposure differs even within the same region, since people’s activities and travel vary. People who resided in an area with high concentrations of common pollutants had higher chances of suffering severe COVID-19 symptoms, which included hospitalization, ICU admission and even death.
Ground-level Ozone had the strongest association. It is an example of gaseous pollution caused by a reaction between sun and air pollutants. Researchers found that those living near high concentrations of the gas were more likely be admitted to ICUs and to die as a result. A higher level of fine particulate material, tiny particles which can enter the bloodstream and penetrate the lungs, was also associated with increased hospitalizations and ICU admissions.
The authors pointed out that these pollutants may not be the only ones that could influence the outcome of disease. Air pollution is a mix of hundreds of interacting gasses and particles, many of which are thought to affect people’s cardiovascular and pulmonary systems.
It is likely that the impact will be even greater elsewhere. Canada consistently ranks among the top countries for air quality. It also has the strictest air pollution regulations anywhere on the planet. Still, “Research over the past several decades [shows] that there is no identified threshold of air pollution level under which adverse health effects from air pollution are absent,” said co-authors Chen Chen, a postdoctoral fellow at University of California San Diego, and Hong Chen, a research scientist for Health Canada, in an email. “This study enforces the idea that air pollution is pervasive and a silent killer.”
This observational study could not establish cause-and effect relationships. Researchers speculate that air pollution may make individuals more susceptible to COVID-19. For instance, air pollution might increase people’s viral loads by limiting the lungs’ immune responses and anti-microbial activities, the study authors say. The body may experience chronic inflammation, and it could trigger an overexpression of the key enzyme receptor used by SARS-2 to enter cells.
Francesca Dominici from Harvard University is an expert in biostatistics and population science. Although she was not part of this current study, Dominici was among the first to establish a link between COVID-19 and pollution. Dominici, who is currently working on a review of the literature, said that she’s identified about 150 papers from around the world showing that exposure to air pollution drives more infections and more severe illness.
But, air pollution is not a threat for everyone. In North America, studies have repeatedly shown that people with lower socio-economic statuses and people of color are more likely to be exposed to air pollution—and suffer worse health outcomes from it—than white people and those with more financial security. They are also more likely to live and work in areas polluted with vehicles and construction. Over time, disparities have become more extreme as industries have moved to places where local communities don’t have the resources to pursue litigation against polluters, says Dominici.
Besides buying air purifiers and filters, which can help reduce an individual’s pollutant exposure somewhat but are often prohibitively expensive, Dominici says, the most effective intervention would be for governments to set stricter standards for emissions. According to Dominici, fine particulate matter has been linked with the greatest number of health problems and therefore requires stricter regulation. “Considering that, unfortunately, it seems we’re going to live with COVID for a very long time, this should be another really important piece of evidence to support implementing stringent regulation for fine particulate matter.”
Improving air quality is essential, say Chen and Chen, because the interaction with COVID-19 may be the “tip of the iceberg” of how air pollution negatively affects human health. “There is a need to continue improving air quality to mitigate air health effects, before they become overwhelming and irreversible.”
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