Exposure to Air Pollution and Changes in Resting Blood Pressure from Morning to Evening: The MobiliSense Study

Several epidemiological studies have documented associations between air pollution exposure and cardiovascular responses, including adverse effects of air pollutants on blood pressure (BP). However, previous studies only considered the effect of specific air pollutants on resting BP, and did not sufficiently consider the independent effects of various air pollution species as well as their overall mixture effect. We addressed this gap in our MobiliSense sensor-based study among 273 participants living in the Grand Paris region. Participants wore personal monitors to assess personal exposure to particles [black carbon and particulate matter smaller than 2.5 μm in diameter (PM_2.5)] and gaseous pollutants [ozone (O₃), nitrogen monoxide (NO), carbon monoxide (CO), and nitrogen dioxide (NO₂)] along with noise exposure. Participants were asked to measure their blood pressure (BP) at rest in the mornings and evenings for three days. Multilevel models with a random intercept at the individual level explored the relationship between air pollution exposure (averaged over the day) and change in resting BP from morning to evening. We also used the quantile G-computation method to estimate the joint effect of the mixture of targeted air pollutants on resting BP. Sensitivity analyses examined the associations between air pollution exposure averaged at different temporal scales before evening BP measurements and the outcome. A quantile increase in the mixture of air pollutants (PM_2.5, NO₂, NO, CO, and O₃) over the day did not affect changes in systolic BP [-0.33 mmHg (95% CI: -3.31, 2.65)] and diastolic BP [-0.53 mmHg (95% CI: -2.66, 1.60)] from morning to evening. When shorter time exposure windows were considered (from a few minutes to a few hours), both NO and the mixture showed positive associations with the morning-to-evening DBP change in only some of the models. Future studies with sufficient repeated BP measurements for more participants should test the association at varying temporal scales (minutes to days) to better understand how air pollution exposure influences resting BP.