Seasonal and COVID-19 lockdown variations in PM2.5 composition to apoptosis pathways and chemical toxicity in lung cells.

OBJECTIVE

To investigate seasonal and COVID-19-lockdown variations in PM2.5 chemical composition in Taipei and the effects of those compositional differences on lung cell toxicity.

METHODS

PM2.5 was collected in warm (2021/07-2021/08) and cold (2021/11-2022/02) seasons and during LV2/LV3 COVID-19 alert periods. Composition (metals, PAHs) was analyzed and A549 and PC9 lung cells were exposed to equal mass concentrations (0-100 μg/mL) of extracted PM2.5. Cell viability, ROS, apoptosis, mitochondrial membrane potential and GSH/GPX4 were measured.

RESULTS

At equivalent mass concentrations (50 μg/mL), warm-season PM2.5 induced higher ROS and greater reduction in viability than cold-season PM2.5. LV2-period PM2.5 contained higher metal content and caused more severe cellular damage than LV3. Spearman correlation plus single-compound assays identified cadmium and Dibenzo[a,e]pyrene as components strongly associated with cytotoxicity.

CONCLUSIONS

Seasonal and human-activity driven compositional changes-rather than mass concentration alone-affect PM2.5 toxicity in vitro; these results underscore the importance of controlling specific chemical emissions.