Evaporative Coolers and Wildfire Smoke Exposure: A Climate Justice Issue in Hot, Dry Regions Authors

Gina M Solomon ^1* Nayamin Martinez ² Julie Von Behren ³ Isabella Kaser ⁴ David Chang ⁴ Aditya Singh ⁵ Stephanie Jarmul ⁶ Shelly Miller ⁷ Peggy Reynolds ³ Mohammad Heidarinejad ⁵ Brent Stephens ⁵ Brett C Singer ⁸ Jeff Wagner ⁹ John Randolph Balmes ^1,10

• ¹ School of Medicine, University of California San Francisco, San Francisco, California, United States
• ² Central California Environmental Justice Network, Fresno, United States
• ³ Department of Epidemiology and Biostatistics, University of California San Francisco, San Francisco, United States
• ⁴ Tracking California, Public Health Institute, Oakland, United States
• ⁵ Department of Civil, Architectual and Environmental Engineering, Illinois Institute of Technology, Chicago, United States
• ⁶ Office of Environmental Health Hazard Assessment, California Environmental Protection Agency, Oakland, United States
• ⁷ University of Colorado Boulder, Boulder, Colorado, United States
• ⁸ Lawrence Berkeley National Laboratory, Berkeley, United States
• ⁹ Environmental Health Laboratory Branch, California Department of Public Health, Richmond, United States
• ¹⁰ Division of Environmental Health Sciences, School of Public Health, University of California, Berkeley, Berkeley, California, United States

Low-income families in dry regions, including in the Southwestern United States, frequently cool their homes with evaporative ("swamp") coolers (ECs). While inexpensive and energy efficient compared to central air conditioners, ECs pull unfiltered outdoor air into the home, creating a health hazard to occupants when wildfire smoke and heat events coincide. A community-engaged research project to reduce wildfire smoke in homes was conducted in California's San Joaquin Valley in homes of Spanishspeaking agricultural workers. 88 study participants with ECs were asked about their level of satisfaction with their EC and their willingness to pay for air filtration. About 47% of participants reported dissatisfaction with their EC, with the most frequently reported reason being that it brings in dust and air pollution. Participants were highly satisfied with air cleaners and air filters that were offered to them freeof-charge. However, a willingness to pay analysis showed that air filtration solutions would not be adopted without significant subsidies; furthermore, air filtration would be an ongoing cost to participants due to the need to regularly replace filters. Short-term filtration solutions for EC users are feasible to implement and may reduce smoke exposure during wildfire events. Such solutions would need to be offered at low-or no-cost to reduce barriers to adoption. Longer term solutions include prioritizing homes with ECs in wildfire smoke exposed regions for replacement with energy efficient air cooling technologies that provide clean air. Because ECs are disproportionately in low-income homes, addressing smoke intrusion through these devices is an environmental justice issue.