Short-Term Exposure to Wildfire Smoke and [Formula: see text] and Cognitive Performance in a Brain-Training Game: A Longitudinal Study of U.S. Adults

BACKGROUND: There is increasing evidence that long-term exposure to fine particulate matter [PM [Formula: see text] in aerodynamic diameter ([Formula: see text])] may adversely impact cognitive performance. Wildfire smoke is one of the biggest sources of [Formula: see text] and concentrations are likely to increase under climate change. However, little is known about how short-term exposure impacts cognitive function. OBJECTIVES: We aimed to evaluate the associations between daily and subdaily (hourly) [Formula: see text] and wildfire smoke exposure and cognitive performance in adults. METHODS: Scores from 20 plays of an attention-oriented brain-training game were obtained for 10,228 adults in the United States (U.S.). We estimated daily and hourly [Formula: see text] exposure through a data fusion of observations from multiple monitoring networks. Daily smoke exposure in the western U.S. was obtained from satellite-derived estimates of smoke plume density. We used a longitudinal repeated measures design with linear mixed effects models to test for associations between short-term exposure and attention score. Results were also stratified by age, gender, user behavior, and region. RESULTS: Daily and subdaily [Formula: see text] were negatively associated with attention score. A [Formula: see text] increase in [Formula: see text] in the 3 h prior to gameplay was associated with a 21.0 [95% confidence interval (CI): 3.3, 38.7]-point decrease in score. [Formula: see text] exposure over 20 plays accounted for an estimated average 3.7% (95% CI: 0.7%, 6.7%) reduction in final score. Associations were more pronounced in the wildfire-impacted western U.S. Medium and heavy smoke density were also negatively associated with score. Heavy smoke density the day prior to gameplay was associated with a 117.0 (95% CI: 1.7, 232.3)-point decrease in score relative to no smoke. Although differences between subgroups were not statistically significant, associations were most pronounced for younger (18–29 y), older ([Formula: see text]), habitual, and male users. DISCUSSION: Our results indicate that [Formula: see text] and wildfire smoke were associated with reduced attention in adults within hours and days of exposure, but further research is needed to elucidate these relationships. https://doi.org/10.1289/EHP10498