UC San Diego

Wildfires are predicted to become more severe and frequent with climate change. Wildfire smoke contains toxic pollutants such as particulate matter 2.5 (PM2.5), which has adverse effects to human health. Literature suggests that air pollution health impacts are cumulative, and wildfire PM2.5 exacerbates pre-existing conditions, potentially contributing to increasing environmental health inequalities. Multiple studies have suggested that communities from low-SES and minority backgrounds are more impacted by air pollution than their counterparts but the role of wildfires’ smoke in health inequalities is still unclear. In this study, we assess the environmental implications of wildfires and wildfire PM2.5 by investigating two mechanisms through which wildfire smoke may contribute to health inequalities: differential exposure and differential susceptibility. We use the 2007 San Diego wildfire storm as a case study along with twelve of CalEnviroScreen 3.0’s environmental justice indicators and run linear aggressions against wildfire PM2.5 and respiratory hospitalizations attributable to wildfire PM2.5. We also produce maps for wildfire PM2.5, excess respiratory hospitalizations, and all twelve indicators for spatial analyses. Overall, we found a null or negative correlation between wildfire PM2.5 and environmental indicators suggesting that low SES communities were less exposed to wildfire smoke during this event. However, we found a positive correlation between respiratory hospitalizations and environmental indicators indicating that low SES communities are systematically more impacted. This suggests that wildfire smoke may contribute to exacerbating environmental injustices through a differential susceptibility mechanism. These findings are important in identifying vulnerable populations and helps inform targeted policies during wildfires events.