Characterization of Residential Woodsmoke PM2.5 in the Adirondacks of New York State

ABSTRACT

Woodsmoke from residential wood heating can be the dominant source of winter PM2.5 in rural areas, but routine monitoring is done primarily in urban or suburban areas. To obtain data on elevated woodsmoke concentrations from nearby sources, PM2.5, black carbon at 880 and 370 nm, particle-bound PAH, and wind speed and direction were measured during winter at three residential locations in Saranac Lake, New York. A paired site design allowed for identification of local sources relative to larger spatial scales. With the exception of occasional regional PM events, hourly PM measurements between paired sites were not well correlated, suggesting elevated PM levels resulted from local woodsmoke influence. One site was located adjacent to a residence with a wood stove, 40 meters away from the measurements, and experienced repeated episodes of elevated PM2.5 concentrations, with a maximum three-hour average of 150 mg/m³. The highest rolling average 24-hour value was 64 mg/m³, and 46 mg/m³ for a midnight to midnight value. Despite these PM events, analysis of the data indicate that this location would be in compliance with the current USEPA PM National Ambient Air Quality Standards (NAAQS). Diel patterns of PM2.5 peaked overnight at all sites, with minimums observed during daytime hours; this is consistent with local ground-level pollution sources such as woodsmoke. The Aethalometer “Delta-C” (DC) woodsmoke indicator data tracked PM2.5 with the same diel pattern. The particle-bound PAH data were not as specific to woodsmoke PM as the DC data, in part because the PAH instrument also responds to traffic particle pollution. One site was repeatedly influenced by 2-cycle snowmobile exhaust in the early evening hours, with very high PAH concentrations but only modestly elevated DC concentrations. Subsequent tests showed that fresh 2-cycle small engine exhaust produces a DC response that is somewhat less than woodsmoke per unit PM concentration.