Abstract

Introduction: Traffic-driven air pollutants levels, such as NO2, have dropped dramatically during COVID-19 lockdowns. Low inhaled UFP (Ultrafine particles) content in exhaled breath condensate (EBC) reflects high inflammatory status of airways and can serve as an indicator of high-level PM exposure. Methods: EBC was collected from 30 healthy subjects during the first lockdown (April 2020) and from 25 healthy subjects during April-June 2016 living in the same northern Israeli district. All participants underwent EBC and blood sampling. Air pollutants levels were collected from the Israeli Ministry of Environmental Protection's database. Data were collected from the monitoring station closest to each subject’s home address and were calculated as an average of 1 month pre EBC performance.  UFP were measured in EBC and blood samples using the NanoSight LM20 system.  Results: The lockdown group was exposed to lower NO2 levels compared to controls- (8.3 vs 11.2 ppb p=0.01). Lower serum-CRP levels were measured in lockdown group compared to controls (0.9 mg/L vs 3.1 mg/L, p=0.056). Lockdown group had higher UFP concentrations in EBC and lower in serum compared to controls (0.58 108/ml and 4.3 108/ml vs 0.43 108/ml and 6.7 108/ml, p=0.05, p=0.03 respectively). NO2 exposure levels (+) correlated both with CRP and UFP concentrations in serum of study population (R= 0.3 and 0.4, p=0.03 and p=0.005, respectively).  Conclusions: Diminished air pollution during COVID-19 lockdowns has impact on airways inflammatory status and reflected in UFP airways contents. High UFP content in EBC and low in subjects' serum during lockdown support our hypothesis that increased epithelial permeability could be the mechanism behind our findings.