Day-to-day particulate exposures and health changes in Los Angeles area residents with severe lung disease

Abstract

We measured particulate matter (PM2.5 and PM10) exposures, home temperature, arterial blood oxygen saturation, blood pressure, and lung function in 30 volunteer Los Angeles area residents during four-day intervals. Continuous Holter electrocardiograms were recorded in a subgroup on the first two days. Subjects recorded symptoms and time-activity patterns in diaries during monitoring, and during a reference period one week earlier/later. All subjects had severe chronic obstructive pulmonary disease. PM10 (24-hr mean) at monitoring stations near subjects' homes averaged 33 micrograms/m3, and ranged from 9 to 84 micrograms/m3. In longitudinal analyses, day-to-day changes in PM2.5 and PM10 outside subjects' homes significantly tracked concurrent station PM10 (r2 = 0.22 and 0.44, respectively). Indoor and personal concentrations were less related to station readings (r2 < or = 0.1), but tracked each other (r2 > or = 0.4). In-home temperatures tracked outdoor temperatures more for lows (r2 = 0.27) than for highs (r2 = 0.10). These longitudinal relationships of subject-oriented and station PM measurements were generally similar to cross-sectional relationships observed previously in similar subjects. Among health measurements, only blood pressure showed reasonably consistent unfavorable longitudinal associations with particulates, more with station or outdoor PM than with indoor or personal PM.