Date of Award
Master of Public Health (MPH)
School of Public Health
Sarah R. Lowe
Exposure to environmental pollutants can have serious consequences for mental health and well-being, leading to widespread societal impacts. With climate change leading to more frequent and severe wildfires, it is increasingly important to understand the impacts of fine particulate matter (PM2.5) from wildfire smoke, a harmful air pollutant that has been shown to impact cognitive health. Burgeoning research has focused on the impact of ambient PM2.5 on mental and neurological health, but little has focused specifically on wildfire smoke PM2.5. This study aimed to examine the relationship between short-term (prior two-week average) and long-term (average during past wildfire season, May-October) exposure to wildfire smoke PM2.5 and symptoms of anxiety and depression among participants in the 2019 National Health and Resilience in Veterans Study (N = 3,511), a nationally representative sample of military veterans in the United States, and to assess whether these relationships are modified by temperature. Symptoms of anxiety and depression were assessed using the Patient Health Questionnaire-4 (PHQ-4), a 4-item validated self-report tool for detecting anxiety and depression over the past two weeks. A multivariable generalized linear regression was applied for the association between long- and short-term exposure to wildfire smoke PM2.5 and composite PHQ-4 score, adding interaction terms for long- and short-term exposure to temperature. In sensitivity analyses, I repeated all models with the separate two-item subscales of anxiety and depression that comprise the PHQ-4. A statistically significant positive association was found between short-term wildfire smoke PM2.5 exposure and PHQ-4 score (B: 0.331, 95% Confidence Interval (CI): [0.069, 0.594]). The addition of an interaction term for short-term temperature was statistically significant (B: 0.072, 95% CI: [0.009, 0.136]) and showed a greater association between wildfire smoke PM2.5 and PHQ-4 score at high temperatures and no significant association at moderate or low temperatures (B: 0.525 at temperature mean + 1SD, 95% CI: [0.212, 0.837]). In sensitivity analyses, a statistically significant positive association was found between short-term wildfire smoke PM2.5 exposure and anxiety subscale score (B: 0.198, 95% CI: [0.054, 0.342]), but not between short-term wildfire smoke PM2.5 and depression subscale score. The addition of an interaction term for short-term temperature was statistically significant (B: 0.061, 95% CI: [0.026, 0.095]) and showed a significant positive association between wildfire smoke PM2.5 and anxiety subscale score at high temperatures and a significant negative association between wildfire smoke PM2.5 and anxiety subscale score at low temperatures, with no significant association at moderate temperatures. No significant main or moderated effects of long-term wildfire smoke PM2.5 exposure on PHQ-4 score or anxiety or depression subscale score were detected. This study provides novel evidence that short-term wildfire smoke PM2.5 is associated with symptoms of anxiety and depression, particularly at high temperatures. Future research should continue to explore the complex relationship between wildfire smoke and mental health.
Goddard, Emily, "Short-Term Exposure To Wildfire Smoke Pm2.5 And Symptoms Of Anxiety And Depression Among U.s. Veterans: A Cross-Sectional Study" (2023). Public Health Theses. 2255.