Between and within-city variations of PM2.5 oxidative potential in five cities in Colombia

Fine particulate matter (PM_2.5) has been shown to cause oxidative stress, which has negative health consequences. The oxidative potential (OP) of PM_2.5 was assessed in five Colombian cities using the synthetic respiratory tract lining fluid assay that tracks the depletion of glutathione (GSH) and ascorbate (AA). For this, a set of 91 integrated 2-week ambient PM_2.5 samples were collected using Ultrasonic Personal Aerosol Samplers (UPAS) at background (5), traffic (37), industrial (12) and residential (37) sites. Across all site types, mean PM_2.5 mass concentration was 20.20 ± 9.36 μg m^-3 The oxidative potential varied widely across cities with an average of 2.67 ± 1.27 for AA and 2.93 ± 1.22 % depletion m^-3 for GSH. OP metrics among cities were not correlated with PM_2.5 mass concentration. Overall, industrial sites showed higher PM_2.5 mass concentrations and OP^AA. In contrast, OP^GSH was not found to differ among industrial, traffic, or residential sites, but was lower for background sites. Our findings provide evidence of substantial between and within-city variations in PM_2.5 OP. Further research is needed to assess the association between OP and adverse health effects.