Ultrafine particle concentrations and exposures in six elementary school classrooms in northern California
Article first published online: 28 OCT 2010
© 2010 John Wiley & Sons A/S
Volume 21, Issue 1, pages 77–87, February 2011
How to Cite
Mullen, N. A., Bhangar, S., Hering, S. V., Kreisberg, N. M. and Nazaroff, W. W. (2011), Ultrafine particle concentrations and exposures in six elementary school classrooms in northern California. Indoor Air, 21: 77–87. doi: 10.1111/j.1600-0668.2010.00690.x
- Issue published online: 5 JAN 2011
- Article first published online: 28 OCT 2010
- Accepted manuscript online: 17 SEP 2010 12:45AM EST
- Received for review 30 December 2009. Accepted for publication 9 September 2010.
- Particle number;
- Indoor–outdoor ratio;
- Condensation particle counter
Abstract Potential health risks may result from environmental exposure to ultrafine particles (UFP), i.e., those smaller than 0.1 μm in diameter. One important exposure setting that has received relatively little attention is school classrooms. We made time-resolved, continuous measurements of particle number (PN) concentrations for 2–4 school days per site (18 days total) inside and outside of six classrooms in northern California during normal occupancy and use. Additional time-resolved information was gathered on ventilation conditions, occupancy, and classroom activity. Across the six classrooms, average indoor PN concentrations when students were present were 5200–16,500/cm3 (overall average 10,800/cm3); corresponding outdoor concentrations were 9000–26,000/cm3 (overall average 18,100/cm3). Average indoor levels were higher when classrooms were occupied than when they were unoccupied because of higher outdoor concentrations and higher ventilation rates during occupancy. In these classrooms, PN exposures appear to be primarily attributable to outdoor sources. Indoor emission sources (candle use, cooking on an electric griddle, use of a heater, use of terpene-containing cleaning products) were seen to affect indoor PN concentrations only in a few instances. The daily-integrated exposure of students in these six classrooms averaged 52,000/cm3 h/day for the 18 days monitored.
This study provides data and insight concerning the UFP exposure levels children may encounter within classrooms and the factors that most significantly affect these levels in an urban area in northern California. This information can serve as a basis to guide further study of children’s UFP exposure and the potential associated health risks.