TITLE:
Infiltration of Black Carbon Particles from Residential Woodsmoke into Nearby Homes
AUTHORS:
Tracy L. Thatcher, Thomas W. Kirchstetter, Christopher J. Malejan, Courtney E. Ward
KEYWORDS:
I/O Ratio, Infiltration Factor, Black Carbon, Woodsmoke Particles, Indoor Exposure
JOURNAL NAME:
Open Journal of Air Pollution,
Vol.3 No.4,
December
2,
2014
ABSTRACT:
In
many communities, residential wood burning is the source of a significant
fraction of wintertime PM2.5 and produces exposures to nearby residents inside
their homes. To evaluate the magnitude of this effect, black carbon particles
were measured as a proxy for woodsmoke indoors and outdoors in a community
where residential woodsmoke is the only significant particle source. Thirteen
indoor/outdoor measurement pairs were obtained at 4 different residences and
showed an average indoor/outdoor concentration ratio of 0.78 ± 0.21 for
residences without indoor generation. In addition, a time dependent mass
balance model was used in conjunction with aethalometer measurements taken over
16 nights at a single residence to estimate an average air exchange rate of
0.26 ± 0.08 h-1, an average deposition loss rate of 0.08 ± 0.03 h-1,
and an average penetration factor of 0.97 ± 0.02. Using a mechanistic approach which utilizes these
average values in a steady state model, the predicted average infiltration
factor was 0.74 for the residence studied. The high values for both measured
I/O ratio and modeled infiltration factor show that residential environments
provide inhabitants with relatively little protection from recently generated
wood smoke particles.