Dynamics of environmental pollution during and after COVID-19 lockdown

COVID-19 lockdowns caused global air pollution declines because of an unprecedented reduction in economic and transport activity. After the relaxation of COVID-19 measures, the environmental pollution has increased again leading to more oxidative stress and systemic inflammation in healthy individuals.

COVID-19-related lockdown resulted in a historic drop in air pollution, that offered a great opportunity to study the effects of air pollutants on human health. The POLCOV study therefore aimed to determine and compare oxidative stress biomarkers and cytokines in healthy individuals during the lockdown and 6 months after easing mobility restrictions in Barcelona [1].

In this prospective study, blood samples were collected during 2 moments from healthy, non-smoking adults. Age, sex, and postal district of residence were collected for all individuals. Blood samples were analysed for eosinophil and Th1/Th2/Th17-related cytokine levels by a multiplex assay. Eotaxin, IFN-γ, IL-7, and RANTES were measured for analysis of regulatory cytokines. In addition, G-CSP, IL-1b, MIP-1α, IL-4, and IL-13 were measured to analyse proinflammatory cytokines. Finally, levels of 8-isoprostane were measured as a biomarker for oxidative stress.

Samples from 58 participants were analysed; mean age was 37 years, most participants were female (62%), and 53% of participants were diagnosed with atopy previously. At the moment of collection of the first sample, the air pollution had been decreased with 80% compared with pre-lockdown. After 6 months, air pollution had reached similar levels to pre-lockdown. At 6 months after the relaxation of COVID-19 restrictions, a significant increase in levels of 8-isoprostane, G-CSF, IL-1β, IL-1ra, IL-4, IL-13, and MIP-1α was found. In contrast, a significant decrease in levels of IFN-γ, TNFα, eotaxin, PDGF-BB, MIP-1β, IL-6, IL-7, and RANTES was observed. No significant differences were observed in the level of eosinophils. Furthermore, levels of other cytokines were not detectable in both periods.

Taken together, biomarkers and cytokines related to oxidative stress and systemic inflammation were found to be significantly increased when environmental pollution increased after easing restrictions due to COVID-19 lockdown.

1. De Homdedeu et al. Late Breaking Abstract - The impact of the reduction of environmental pollution during COVID-19 lockdown on healthy individuals (POLCOV Study). Abstract 3255. ERS 2021, 5–8 September.

 

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Posted on 9 November 2021