Personal exposure to fine particles, inflammation and oxidative stress among commuters before, during and after COVID-19 outbreak in Taipei

The association between fine particles exposure and adverse health effects during commuting has been reported in previous studies. However, knowledge about whether wearing masks has a protective effect on commuters’ air pollution exposure and related health effect is still limited. Therefore, the present study recruited 200 healthy participants in Taipei before, during and after the coronavirus disease 2019 (COVID-19) epidemic. All participants were required by law to wear masks when going out during the COVID-19 epidemic. Each participant was classified by his/her own commuting style, including subway, scooter, and walking. Three repeated measurements of inflammation marker, interleukin 6 (IL-6) and oxidative stress marker, 8-hydroxy-2-deoxyguanosine (8-OHdG) in sputum and urine, particulate matter with an aerodynamic diameter ≤2.5 μm (PM_2.5), temperature, and humidity were conducted for each participant during commuting. Mixed-effects models were used to investigate the association of PM_2.5 with IL-6 or 8-OHdG in sputum or urine before, during and after the COVID-19 epidemic. The study results showed that personal PM_2.5 exposure level (Mean ± standard deviation) was highest in the scooter group (52.1 ± 22.3 μg/m³) but lowest in the subway group (22.6 ± 9.7 μg/m³). Personal exposure to PM_2.5 was associated with increased IL-6 or 8-OHdG in sputum or urine before and after the COVID-19 epidemic among all groups. The effect of PM_2.5 on IL-6 or 8-OHdG in sputum or urine was not statistically significant in subway group or walking group during the COVID-19 epidemic. By naturally observing the phenomenon of commuters wearing masks before, during and after the COVID-19 epidemic, we suggest that wearing masks during commuting could be one of the preventive measures to reduce air pollution exposure.