— Continued efforts to reduce ambient air pollution levels are needed, researchers say
Long-term exposure to ambient air pollution was associated with an increased risk of long COVID among young adults, according to a Swedish population-based cohort study.
For each increase in interquartile range (IQR) in exposure to particulate matter ≤2.5 μm (PM2.5) in 2019 (median annual exposure 6.39 μg/m3), the odds of developing long COVID increased by about 30%, reported Erik Melén, MD, PhD, of the Karolinska Institutet in Stockholm, and co-authors.
The adjusted odds ratio of PM2.5 per IQR increase was 1.28 (95% CI 1.02-1.60) for long COVID, while the odds ratios were 1.65 (95% CI 1.09-2.50) for dyspnea symptoms and 1.29 (95% CI 0.97-1.70) for altered smell/taste, Melén and team noted in Lancet Regional Health – Europeopens in a new tab or window.
Associations tended to be stronger for participants with asthma, and those who had COVID in 2020 compared with 2021, they added.
“Ambient air pollution exposure have been shown to be positively associated with increased levels of inflammatory cytokines and proteins, which have been proposed as possible causes of multiple symptoms of post COVID-19 conditions,” Melén and team wrote. “In addition, air pollution has been found to be associated with immune dysregulation including immune suppression, which was reported to be associated with risk of persistent symptoms after COVID-19.”
“The virulence of the SARS-CoV-2 virus may be altered in polluted regions as a contributing mechanism,” they continued. “Furthermore, long-term air pollution exposure can have adverse effects on a wide range of comorbidities such as cardiometabolic diseases and respiratory diseases, which have been found to be associated with risk of developing long COVID. This is consistent with our results that the observed association tended to be stronger among participants with asthma.”