A study presented at the European Congress of Clinical Microbiology & Infectious Diseases (ECCMID) held online this year shows that long-term exposure to high levels of air pollutants, specifically, fine particulate matter (PM2.5), has significantly influenced the outcomes for people hospitalized with COVID-19.
Researchers say that more exposure leads to a higher risk. Every small (µg/m3) increase in the long-term PM2.5 exposure is linked to more than thrice the chances of being mechanically ventilated and two times the chances of likely staying in ICU.
Our study calls attention to the systemic inequalities that may have led to the stark differences in COVID-19 outcomes along racial and ethnic lines. Communities of color are more likely to be located in areas closer to industrial pollution, and to work in businesses that expose them to air pollution.
Dr Anita Shallal, Henry Ford Hospital
The American Lung Association reports that Detroit is the 12th most polluted city in the United States, as measured by year-round fine particle pollution (PM2.5). Ambient air pollution with potential harmful pollutants such as PM2.5 and toxic gases emitted by industries, vehicles, and households can increase inflammation and oxidative stress in the respiratory system, worsening already existing lung disease.
Air pollution is associated with worse health outcomes, such as the higher risk of dying from respiratory viruses like influenza.
The researchers analyzed the relation between air pollution and the severity of COVID-19 outcomes by retrospectively examining information from 2,038 adults affected by COVID-19 admitted to four large hospitals within the Henry Ford Health System from March 12th to April 24th, 2020. A follow-up of the patients was continued until May 27th, 2020.
Data related to participants’ residence and data regarding sources of local levels of pollutants, including PM2.5, ozone, and lead paint (percentage of houses built before 1960), from the US Environmental Protection Agency were collected. The link between COVID-19 outcomes and exposure to ozone, PM2.5, traffic, lead paint, wastewater discharge, and hazardous waste was investigated.
The researchers discovered that patients who were male, obese, black, or had more severe long-term health conditions were much more likely to be mechanically ventilated and admitted to the ICU. This was also the case for patients who reside in areas with higher levels of PM2.5 and lead paint.
Even after taking the potentially influential factors such as age, BMI, and underlying health conditions into account, the study revealed that being male, obese, and having more severe long-term health conditions were a good predictor of possible death following admission. Higher PM2.5 was an independent predictor for mechanical ventilation and ICU but does not necessarily associate with the risk of dying from COVID-19.
The key takeaway is that living in a more polluted neighborhood is an independent risk factor for severity of COVID-19 disease. Although it is not clear how air pollutants contribute to more severe disease, it’s possible that long-term exposure to air pollution may impair the immune system, leading both to increased susceptibility to viruses and to more severe viral infections.
Dr Anita Shallal, Henry Ford Hospital
“In a double hit, fine particles in air pollution may also act as a carrier for the virus, increasing its spread. Urgent further research is needed to guide policy and environmental protection, to minimize the impact of COVID-19 in highly industrialized communities that are home to our most vulnerable residents,” concluded Dr Shallal.
According to the researchers, the study was observational and thus the cause cannot be established. Moreover, they adjusted for various influential factors, but it could still be that other factors that could not be fully controlled for, such as the severity of disease at the time of presentation, may contribute to the observed outcomes.