Ambient air pollution and oxygen saturation.

We investigated the association between fine particulate air pollution and oxygen saturation as measured with a peripheral oxygen saturation monitor during a 12-week repeated-measures study of 28 older Boston residents. Oxygen saturation and air pollution particulates with a mean diameter less than or equal to 2.5 microm were measured continuously during a protocol of rest, standing, exercise, postexercise rest, and 20 cycles of slow, paced breathing. In fixed-effect models, mean pollution concentration was associated with reduced oxygen saturation during the baseline rest period (6 hours: mean, -0.173%; 95% confidence interval [CI], -0.345 to -0.001), postexercise (6 hours: mean, -0.173%; 95% CI, -0.332 to -0.014), with a trend toward decrease during postexercise paced breathing (6 hours: mean, -0.142%; 95% CI, -0.292 to 0.007) but not during exercise. Participants taking beta-blockers had a greater pollution-related decrease in oxygen saturation at rest (6 hours: mean, -0.769%; 95% CI, -1.210 to -0.327) (interaction for particulates with a mean diameter less than or equal to 2.5 microm by beta-blocker, p < 0.0005) than did those not taking beta-blockers (p > 0.25). The reduction in oxygen saturation associated with air pollution may result from subtle particulate-related pulmonary vascular and/or inflammatory changes. Further investigation may contribute to our understanding of the mechanisms through which particulates may increase respiratory and cardiac morbidity among vulnerable populations.