Poster at ISEE 2024

Abstract Dual exposure to power outages and wildfire PM2.5 in California among vulnerable populations

Lauren B Wilner, Caitlin Ngo-Jones, Tarik Benmarhnia, Joan A. Casey

Objective: Climate change has driven a substantial increase in the frequency, duration, and intensity of wildfires in California. There is mounting concern over electrical utility infrastructure failing due to wildfires, which could exacerbate wildfire health effects.1 As such, the state may now preemptively de-energize power lines, referred to as public safety power shutoffs (PSPS), to reduce risk.1 While the intention is increased public safety, PSPS events result in power outages that may harm the same people they attempt to protect. This study aims to describe the extent of dual wildfire-PSPS exposure and the vulnerability of the populations that they affect.

Methods: We use CDC emPOWER data2 and PSPS data from California3 to examine the largest PSPS events – those affecting over 20% census tract population for 8 hours or more. The analysis overlays PSPS events in time/space over wildfire fine particulate matter (PM2.5) levels by county to quantify the extent of dual exposure to wildfire PM2.5 and power outages from the PSPS event.

Results: From 2018-2021, there were 70 large PSPS events, and 11 that affected 20% or more of the population. During these events, 74% of the associated county-days had elevated mean wildfire PM2.5 levels (range: 0.1 – 74.2 μg/m3). In these counties, based on CDC emPOWER data, we estimated an average of 13,734 Medicare beneficiaries and an average of 574 individuals using electricity-dependent durable medical equipment (DME), with as many as 2,446 individuals dependent on DME.

Conclusion: PSPS events intend to prevent wildfires, but often co-occur with them. These dual events also co-occur in areas with high prevalence of vulnerable individuals. Identifying and understanding the dual exposure and the populations affected is essential to ensuring that people have the infrastructure needed to remain safe during wildfire-preventive outages. Future studies should assess the health risks of dual PSPS-wildfire PM2.5 exposures.