U.S. Study Shows That Exposure To Air Pollutants Can Exacerbate The Effects Of A COVID-19 Infection

COVID-19 Research: A new study by researchers from the Keck School Of Medicine at the University of Southern California has shown that exposure to air pollutants can exacerbate the effects of a COVID-19 infection.


 
Although numerous past ecological studies have shown air pollution associations with COVID-19 outcomes, few proper cohort studies have been conducted at assess the effects of air pollutants on SARS-CoV-2 infections.
 
The COVID-19 Research team aimed to conduct a cohort research investigating the association between air pollution and COVID-19 severity using individual-level data from electronic medical records.
 
The cohort included all individuals diagnosed with COVID-19 from Kaiser Permanente Southern California between 3/1/2020 and 8/31/2020. 1-year and 1-month averaged ambient air pollutant (PM2.5, NO2 and O3) exposures before COVID-19 diagnosis were estimated based on residential address history. Outcomes included COVID-19-related hospitalizations, intensive respiratory support (IRS), and intensive care unit (ICU) admissions within 30 days, and mortality within 60 days after COVID-19 diagnosis. Covariates included socio-characteristics and comorbidities.
 
Among 74,915 individuals (mean age 42.5 years, 54% female, 66% Hispanic), rates of hospitalization, IRS, ICU, and mortality were 6.3%, 2.4%, 1.5% and 1.5% respectively.
 
The study findings utilizing multi-pollutant models adjusted for covariate found that 1-year PM2.5 and 1-month NO2 average exposures were associated with COVID-19 severity.
 
The odds ratios (ORs [95% CI]) associated with one standard deviation (SD) increase in 1-year PM2.5 (SD 1.5 µg/m3) were 1.24 [1.16-1.32] for COVID-19-related hospitalization, 1.33 [1.20-1.47] for IRS, 1.32 [1.16-1.51] for ICU; the corresponding ORs [95% CI] associated with 1-month NO2 (SD 3.3 ppb) were 1.12 [1.06-1.17] for hospitalization, 1.18 [1.10-1.27] for IRS, and 1.21 [1.11-1.33] for ICU. The hazard ratios (HR [95% CI]) for mortality were 1.14 [1.02-1.27] for 1-year PM2.5 and 1.07 [0.98-1.16] for 1-month NO2.
 
No significant interactions with age, sex or ethnicity were observed.
 
The study findings hence concluded that ambient PM2.5 and NO2 exposures may affect COVID-19 severity and mortality.
 
The study findings were published in the peer reviewed American Journal of Respiratory and Critical Care Medicine. https://www.atsjournals.org/doi/10.1164/rccm.202108-1909OC
 
The study findings shows a significant increase in the risk of severe outcomes for COVID-19 patients exposed to fine particles (PM2.5) and nitrogen dioxide (NO2), two common (and correlated) components of ambient air pollution in Southern California. Produced by ground and air traffic, industrial burning and other sources, these air pollutants can exacerbate the effects of the SARS-CoV-2 virus over both the short and long term.
 
The study demonstrated that one-year average exposure to PM2.5 translated to a 20-30 percent increase in the risk of hospitalization, intensive respiratory support and ICU admissions from COVID-19. Exposure to NO2 for one month carried an increased risk o f 12-18 percent.
 
Co-first author of the study, Dr Zhanghua Chen, assistant professor of population and public health sciences at the Keck School of Medicine of USC told Thailand Medical News, “We also saw that long-term PM2.5 exposure was associated with a higher risk of mortality from COVID-19."
 
The study team collaborated with Kaiser Permanente Southern California (KPSC) to examine a cohort of more than 74,000 COVID-19 patients diagnosed from March to August 2020. With detailed residential address history linked to Kaiser Permanente members' electronic medical records (EMR), the study team were able to accurately predict exposure history for specific pollutants.
 
In the early part of the pandemic, a number of studies using national data in ecological analyses found a link between long-term air pollution exposure and increased COVID-19 incidence and mortality. However, this approach raised important questions and concerns.
 
Dr Chen added, "Ecological analyses are subject to a lot of biases, and it wasn't clear whether the findings could be applied beyond the community level. In our population cohort study, we were able to leverage the sophistication of EMR to create a well-defined classification of the severity of COVID-19 outcomes tied to air pollution exposure at the individual level."
 
The study findings were clear, noted coauthor and Professor of Population and Public Health Sciences, Dr Frank Gilliland, MD, PhD.
 
He added, "Our research demonstrates that breathing clean air may reduce the severity of the infection. When someone is infected, reducing their exposure to air pollutants maybe beneficial, as it may decrease the risk for poor outcomes and also has many other health benefits."
 
Besides providing individual-level results, utilizing the Kaiser Permanente cohort for the study conferred other benefits as well.
 
Corresponding author Anny Xiang, PhD, MS, a senior research scientist at KPSC's Department of Research & Evaluation added, "Kaiser Permanente has enriched patient background information also known as covariates, encompassing factors including race, ethnicity, sex and socioeconomic status, which enabled us to adjust for social demographics and comorbidities like diabetes, obesity and asthma. Also, whereas other studies were more focused on older populations, which are more susceptible to COVID-19, ours has a much broader representation of age range because Kaiser Permanente covers such a large percentage of Southern California residents."
 
The study team based on their findings, now plan to examine intervention approaches such as using air purifiers to reduce individual levels of PM2.5 exposure.
 
Messrs Xiang added, "We're starting some crossover clinical trials to investigate these types of strategies on a personal level, to see whether they can help reduce cardiometabolic disease risk.”
 
Thailand Medical News would like to further add that cigarette smoke, smoke from incense sticks can all also increase COVID-19 severity and the same goes for pollutants emitted from home, office air, hotel and spa air diffusers that use various aromatic oils.


 
The study team also included Dr Brian Huang, Dr Sandrah Eckel, Dr Roya Gheissari and Dr Duncan Thomas from the Keck School of Medicine; Dr Margo Sidell, D Ting Chow, and Dr Mayra Martinez from Kaiser Permanente Southern California; and Fred Lurmann from Sonoma Technology, Inc.
 
The research was supported by the U.S. National Institute of Environmental Health Sciences (3R01ES029963-01) and the Keck School of Medicine Department of Preventive Medicine COVID-19 Pandemic Research Center at USC.
 
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