List of Wildfire Studies Conducted by OEHHA

Last updated: February 2026

• Syed, A., Chen, C., Benmarhnia, T., & Basu, R. (2026). The joint effects of extreme heat and wildfire smoke on paediatric acute care utilisation. Paediatric and Perinatal Epidemiology, 40(1), 112–121. https://doi.org/10.1111/ppe.70080
  • Main Findings: The study found synergistic effects of extreme heat and wildfire smoke on children’s health especially on pediatric emergency room visits and hospital admissions related to infectious enteritis, heat-related illness, asthma, endocrine, nutritional, and metabolic disease, and respiratory disease.
• Syed, A., & Basu, R. (2025). The effect of wildfire smoke on children's health: A systematic review. Paediatric and Perinatal Epidemiology, 39(1), 110–119. https://doi.org/10.1111/ppe.13141
  • Main Findings: The review found consistent evidence that wildfire exposure is associated with adverse respiratory health in children and less consistent evidence for the effect on non-respiratory outcomes. Higher risk children were identified as asthmatic, obese, under the age of five, in low-income countries, or with a low socioeconomic status.
• Ha, S., Abatzoglou, J. T., Adebiyi, A., Ghimire, S., Martinez, V., Wang, M., & Basu, R. (2024). Impacts of heat and wildfire on preterm birth. Environmental Research, 252(Pt 4), 119094. https://doi.org/10.1016/j.envres.2024.119094
  • Main Findings: Wildfire smoke days were linked to an increased risk of preterm birth. The odds of preterm birth rose by about 3% on smoke days, with stronger effects observed among Black, Hispanic, Asian, and American Indian/Alaska Native individuals compared to White participants. Heatwave days also increased the risk of preterm birth by about 7%, and this risk rose to 19% when heatwaves coincided with wildfire smoke days.
• Chen, A. I., Ebisu, K., Benmarhnia, T., & Basu, R. (2023). Emergency department visits associated with wildfire smoke events in California, 2016–2019. Environmental Research, 238(Pt 1), 117154. https://doi.org/10.1016/j.envres.2023.117154
  • Main Findings: Wildfire smoke event days were associated with increased emergency department visits for respiratory conditions, especially for asthma and chronic lower respiratory disease. Cardiovascular visits also increased. Mixed findings were reported for mental health, but short-term exposure was linked to more visits for schizophrenia.
• Darling R, Hansen K, Aguilera R, Basu R, Benmarhnia T, Letellier N. (2023). The Burden of Wildfire Smoke on Respiratory Health in California at the Zip Code Level: Uncovering the Disproportionate Impacts of Differential Fine Particle Composition. GeoHealth, 7(10), 1-11. https://doi.org/10.1029/2023GH000884
  • Main Findings: A health impact assessment was carried out to evaluate the effects of PM_2.5 on respiratory hospitalizations in California between 2006 and 2019. The study's findings indicate that the health impact of hospitalizations attributable to PM_2.5 may be underestimated by not accounting for the PM_2.5 generated by wildfires.
• Aguilera, R., Luo, N., Basu, R., Wu, J., Clemesha, R., Gershunov, A., & Benmarhnia, T. (2023). A novel ensemble-based statistical approach to estimate daily wildfire-specific PM_2.5 in California (2006-2020). Environment International, 171, 107719. https://doi.org/10.1016/j.envint.2022.107719
  • Main Findings: An ensemble model was used to generate daily wildfire-specific PM_2.5 at the ZIP code level for a 15-year period (2006-2020).
• Heaney, A., Stowell, J. D., Liu, J. C., Basu, R., Marlier, M., & Kinney, P. (2022). Impacts of Fine Particulate Matter from Wildfire Smoke on Respiratory and Cardiovascular Health in California. GeoHealth, 6(6), e2021GH000578. https://doi.org/10.1029/2021GH000578
  • Main Findings: Smoke event days, which are defined as days with high levels of wildfire PM_2.5, increased the risk of respiratory hospital admissions, with particularly profound effects among children aged 0-5 years. Smoke event days have also been found to increase the risks of cardiovascular hospital admissions among non-Hispanic White individuals and those older than 65 years, and this risk is particularly high in conjunction with high temperature days.
• Schwarz, L., Dimitrova, A., Aguilera, R., Basu, R., Gershunov, A., & Benmarhnia, T. (2022). Smoke and COVID-19 case fatality ratios during California wildfires. Environmental Research Letters, 17(1), 014054. https://doi.org/10.1088/1748-9326/ac4538
  • Main Findings: The study found that COVID-19 case fatality ratios (CFRs) increased during wildfire events in the San Francisco Bay Area in 2020. The findings suggest that extreme weather events such as wildfire smoke can increase vulnerability to infectious diseases.
• Malig, B. J., Fairley, D., Pearson, D., Wu, X., Ebisu, K., & Basu, R. (2021). Examining fine particulate matter and cause-specific morbidity during the 2017 North San Francisco Bay wildfires. The Science of the Total Environment, 787, 147507. https://doi.org/10.1016/j.scitotenv.2021.147507
  • Main Findings: During the October 2017 Northern California wildfire period, short-term exposure to PM_2.5 increased the risk of emergency room visits and hospital admissions for respiratory disease, such as asthma. The effects during the wildfire period were stronger than during a non-wildfire period.
• Holm, S. M., Miller, M. D., & Balmes, J. R. (2021). Health effects of wildfire smoke in children and public health tools: a narrative review. Journal of Exposure Science & Environmental Epidemiology, 31(1), 1–20. https://doi.org/10.1038/s41370-020-00267-4
  • Main Findings: Children remain especially vulnerable to wildfire smoke for both physiological and behavioral reasons. This review summarizes current knowledge and knowledge gaps in the health effects of wildfire smoke in children and identifies tools for public health response aimed at children, including consideration of low-cost sensor data, respirators, and exposures in school environments. Surgical masks, respirators, and better filtration systems at school can help alleviate some of the risks that wildfire smoke poses for children.
• Liu, J. C., Wilson, A., Mickley, L. J., Dominici, F., Ebisu, K., Wang, Y., Sulprizio, M. P., Peng, R. D., Yue, X., Son, J. Y., Anderson, G. B., & Bell, M. L. (2017). Wildfire-specific Fine Particulate Matter and Risk of Hospital Admissions in Urban and Rural Counties. Epidemiology, 28(1), 77–85. https://doi.org/10.1097/EDE.0000000000000556
  • Main Findings: Among Medicare enrollees in the Western U.S., smoke wave events were associated with increased risk of respiratory hospital admissions when compared to non-smoke wave days. Specifically, PM_2.5 from wildfires may contain a higher concentration of toxic chemicals constituents than PM_2.5 from other sources.
• Liu, J. C., Wilson, A., Mickley, L. J., Ebisu, K., Sulprizio, M. P., Wang, Y., Peng, R. D., Yue, X., Dominici, F., & Bell, M. L. (2017). Who Among the Elderly is Most Vulnerable to Exposure to and Health Risks of Fine Particulate Matter from Wildfire Smoke? American Journal of Epidemiology, 186(6), 730–735. https://doi.org/10.1093/aje/kwx141
  • Main Findings: Between 2004 and 2009, higher proportions of people who were Black and who lived in urban counties in California were more likely to be exposed to smoke waves in the Western U.S. Additionally, the risk of respiratory admissions from wildfire smoke was significantly higher for women compared to men (10.4% vs. 3.7%) and for Black people compared to White people (21.7% vs. 6.9%).
• Liu, J. C., Mickley, L. J., Sulprizio, M. P., Dominici, F., Yue, X., Ebisu, K., Anderson, G. B., Khan, R. F. A., Bravo, M. A., & Bell, M. L. (2016). Particulate Air Pollution from Wildfires in the Western US under Climate Change. Climatic Change, 138(3), 655–666. https://doi.org/10.1007/s10584-016-1762-6
  • Main Findings: With future climate change (2046-2051) in the Western U.S., it is estimated that over 82 million people will experience a 57% increase in the frequency and a 31% increase in the intensity of smoke waves, defined as high levels of wildfire-specific PM_2.5.