Pilot Study of the Effect of Personalized Monitoring Results on Home Occupants’ Perceptions of Air Pollution Health Risks

This pilot study explored whether receiving personalized indoor air quality results influences occupants’ knowledge and risk perceptions related to air pollution exposure. In 2022–2023, the “Air Conditioning Wildfire Smoke Study” measured indoor and outdoor PM2.5 and ozone (O3) levels in 31 homes in Utah County. These data were used to generate individualized letters comparing each home’s (n = 16) pollutant levels to the U.S. Environmental Protection Agency’s Air Quality Index. Participants completed surveys at baseline and approximately 90 days after receiving their letter. For primary outcomes, we observed a significant decrease from pre- to post-test for perceived threat for O3 (p = 0.019). There was no meaningful or significant change in risk perception measures for PM2.5. Total pollutant knowledge (O3 + PM2.5) positively and significantly increased (32%). For exploratory outcomes, participants with lower indoor PM2.5 and O3 levels relative to outdoor concentrations tended to have a larger decrease in risk perception after the intervention. The PM2.5 trend was statistically significant as evaluated with a ranked Spearman correlation coefficient (ρ = 0.65, 95% CI [0.11, 0.97]), whereas the descriptive trends indicated that perceived threat regarding O3 decreased mainly in households using central air conditioning that had O3 levels below the limit of detection. Decreased threat for O3 may reflect improved alignment between participants’ risk perceptions and relatively low indoor pollution levels. However, we cannot attribute the decrease in risk perception to our intervention due to study limitations. In the preliminary exploratory analyses, a possible divergence is noted: total threat regarding air pollution seemed to fall among participants who reported not engaging in protective behavior or making home changes in response to outdoor air pollution, while it remained fairly stable among those who made changes. Because the sample size was small, these subgroup findings are hypothesis-generating and highlight the need for further study in large groups. Findings should be interpreted in light of key limitations, including small sample size (n = 15), short monitoring periods (1–5 days), measurements conducted under low indoor pollution conditions, lack of a control group, and the use of outdoor regulatory standards to contextualize indoor air quality in the absence of established residential guidelines.