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, a promising health exposure metric, was assessed in five Colombian cities using the synthetic respiratory tract lining fluid assay that tracks the depletions of glutathione and ascorbate. 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 (OP^AA for ascorbate and OP^GSH for glutathione) 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 concentrations. 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 substantial evidence of variations in PM_2.5 OP between cities and within the cities. Further research is needed to assess the association between OP and adverse health effects, as well as to attribute the sources that cause such variations.