Key factors for selecting PM2.5 and ozone exposure assessment methods in epidemiological studies

Environmental epidemiological studies often use both station-monitored and personal air pollutant exposures, which frequently yield different results. We aimed to identify key considerations when choosing between these measures. In a panel study of 37 college students assessed six times across three seasons for cardiorespiratory outcomes, personal PM 2.5 and O 3 exposures were monitored for 5 days with wearable sensors before each health assessment, alongside concurrent measurements from nearby monitoring stations. The association between station-monitored and personal concentrations was stronger for PM 2.5 (regression coefficient: 0.51 ± 0.16) than for O 3 (regression coefficient: 0.19 ± 0.15). Both station-monitored and personal PM 2.5 were associated with decreased forced expiratory volume in the first second (FEV 1 ), forced vital capacity (FVC), and increased fractional exhaled nitric oxide (FeNO). In contrast, only station-monitored O 3 was associated with decreased FEV 1 , FVC, increased FeNO, and worsening augmentation index (AI) and blood pressure. Personal O 3 showed mostly null associations or even “seemingly beneficial” associations with AI, FEV 1 , and FVC. These findings suggest station-monitored PM 2.5 can serve as a reasonable proxy for personal exposure in studies with minimal indoor PM 2.5 sources. However, this may be unsuitable for O 3 , given its high spatial variability and potential differences in exposure to ozone-derived reaction products.