Abstracts: ISEE 21st Annual Conference, Dublin, Ireland, August 25–29, 2009: Oral Presentations
Background and Objective:
Residential wood burning has been linked to respiratory morbidity and is a significant pollution source in many locations. However, little is known about the cardiovascular effects of air pollution in woodsmoke-impacted communities.
Using portable high efficiency particulate air (HEPA) filters in an intervention study, we investigated air pollution and microvascular function among approximately 50 healthy adults in a woodsmoke-impacted community in British Columbia, Canada. In a single-blind randomized crossover design, each home was monitored for two consecutive seven-day periods, and two HEPA units were operated indoors with the filters removed for one of the two periods. Air pollution was measured indoors and outdoors using nephelometers for continuous PM2.5 mass concentration and Harvard Impactors for both PM2.5 mass concentration and the woodsmoke tracer levoglucosan. Microvascular function was measured at the end of each seven-day period using the portable Endo-PAT. In addition, inflammatory markers in blood (C-reactive protein and interleukin-6) and urinary oxidative stress markers (isoprostanes and malondialdehyde) were also quantified, and participants completed a respiratory symptoms questionnaire and time-location diary.
Based on preliminary monitoring results from 14 homes, the average outdoor PM2.5 concentration was 11.3 ± 5.4 μg/m3 and was not related to HEPA filter status. As expected, indoor concentrations were significantly lower during HEPA filtration periods (3.5 ± 2.1 μg/m3) than during non-HEPA periods (9.8 ± 6.2 μg/m3). The indoor PM2.5 reduction in individual homes ranged between 0.4 and 15.8 μg/m3 (median reduction: 5.2 μg/m3), with a greater reduction in the indoor-generated PM2.5 component (median reduction: 3.6 μg/m3) than the outdoor-generated component (median reduction: 1.4 μg/m3). Levoglucosan will allow us to evaluate the role of woodsmoke in these PM2.5 reductions.
These preliminary results indicate that HEPA filters reduce indoor PM2.5 and introduce modest exposure gradients from which to evaluate woodsmoke-influenced PM2.5 and cardiovascular health.