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Understanding Ultrafine Particles Indoors
This page updated December 23, 2009
Chair’s Air Pollution Seminar |
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Tuesday, February 2, 2009
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Understanding Ultrafine
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William W. Nazaroff,
Ph.D.
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Field monitoring of
ultrafine particles and copollutants was undertaken at seven houses and
six classrooms in the East Bay region near San Francisco,
California. At each site, time-resolved measurements were
made indoors and outdoors of particle number (PN) concentration in
addition to nitric oxide, ozone, carbon dioxide and carbon
monoxide. Data were also acquired through the use of
questionnaires (houses), observation (classrooms), and temperature and
proximity sensors. The information from each site were
analyzed to characterize (1) indoor and outdoor PN concentrations; (2)
key factors that influence indoor PN concentrations; and (3) the
exposure of building occupants to indoor PN and its determinants. During observational monitoring, the time-averaged PN concentrations from the primary indoor monitor varied across the seven house sites from 3.7 x 103 particles per cm3 to 28 x 103 particles per cm3 (averaging 14.5 x 103 particles per cm3). The corresponding outdoor concentrations ranged from 5.5 x 103 to 23 x 103 particles per cm3 (averaging 15 x 103 particles per cm3). For five classroom sites (excluding one at which overnight outdoor data were incomplete), the time-average indoor concentrations ranged from 3.2 x 103 to 10.5 x 103 particles per cm3 (averaging 6.9 x 103 particles per cm3); the corresponding outdoor concentrations ranged from 9.7 x 103 to 16 x 103 particles per cm3 (averaging 13 x 103 particles per cm3). Overall, the results inform the interplay among building factors, human occupancy, and pollutant dynamics as they influence concentrations of and exposures to ultrafine particles in the studied houses and classrooms. Particle levels in classrooms and in houses were much higher when occupied than when vacant. In houses, important contributions to PN levels were attributable to both outdoor particles and indoor emission sources such as cooking (both with natural gas and electricity) and natural gas furnace use. In schools, the dominant PN source was outdoor air and indoor levels were significantly influenced by time-varying ventilation conditions. Daily average PN exposures per person were much higher in houses than in schools.ted parties.
William W. Nazaroff,
Ph.D., is
Daniel Tellep Distinguished Professor and Vice-Chair for Academic
Affairs in the Civil and Environmental Engineering Department, University of California,
Berkeley. Dr. Nazaroff joined the faculty there two
decades ago after receiving his education in Physics (BA, UC Berkeley,
1978), Electrical Engineering and Computer Science (MEng, UC Berkeley,
1980), and Environmental Engineering Science (PhD, Caltech,
1989). Professor Nazaroff's research group focuses on the
physical science and engineering aspects of air pollution exposure,
with a special emphasis on indoor environments. Dr. Nazaroff
served on ARB’s Research Screening Committee (2000-2002). At
present, he serves as Vice-President Elect of the American Association
for Aerosol Research (AAAR), as coeditor of Indoor Air, and as Vice
President of the Academy of Fellows of the International Society of
Indoor Air Quality and Climate. Dr. Nazaroff is author and
coauthor of over 120 research articles published in archival journals
and coauthor
(with L Alvarez-Cohen) of the textbook, Environmental Engineering
Science (Wiley, 2001).
For information
on this Series please contact: For
a complete listing of the ARB Chairman's Series and the related
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