Air Pollution Exposure Induces a Decrease in Type II Interferon Response: A Paired Cohort Study

Background: While air pollution is a major issue due to its harmful effects on human health, few studies focus on its impact on the immune system and vulnerability to viral infections. The lockdown declared following the COVID-19 pandemic represents a unique opportunity to study the large-scale impact of variations in air pollutants in real life. We hypothesized that variations in air pollutants modify the antiviral response represented by interferon (IFN) γ production.Methods: We conducted a single center paired cohort study of 58 participants in Nice (France), with an initial sampling during lockdown between March 2020 and June 2020, and the second sampling in the post-lockdown period between September 2020 and January 2021. We correlated the variations in the production of IFNγ after non-specific stimulation of participants’ immune cells with variations in key regulated pollutants: NOx, NO2, NO, O3, PM2.5, and PM10 and climate variables. Using linear regression, we studied the effects of variations of each pollutant on the immune response.Findings: IFNγ production significantly decreased by 37% post-lockdown compared to during lockdown, while NO2 and NOx increased significantly by 46% and 91%, respectively. After the adjustment for climate variations during the study period (sunshine and temperature), we observed a significant effect of NO2 variation on IFNγ production (-9.582 IU/mL).Interpretation: We show a weakening of the antiviral cellular response in correlation with increased exposure to nitrogen dioxide independently of all other climatic variations measured over this period.Funding: None to declare. Declaration of Interest: None to declare. Ethical Approval: This study was reviewed and approved by our local institutional review committee (NCT04429594 and NCT04355351).