1. ^aHealthy Environments and Consumer Safety Branch, Health Canada, Ottawa, Ontario, Canada
2. ^bDepartment of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario, Canada
3. ^cToronto Public Health, Toronto, Ontario, Canada
4. ^dEnvironment Canada, Toronto, Ontario, Canada

Correspondence: Dr. D.M. Stieb, Biostatistics and Epidemiology Division, Healthy Environments and Consumer Safety Branch, Health Canada, 269 Laurier Avenue W., 3rd Floor, 3-029, Ottawa, Ontario, Canada PL4903c. Tel.: +613 957 3132; Fax: +613 954 7612; E-mail: dave_stieb@hc-sc.gc.ca

Received 16 February 2007; Accepted 7 September 2007; Published online 5 December 2007.

Abstract

We evaluated the impact on personal exposure to air pollutants of following advice which typically accompanies air quality advisories and indices. Scripts prescribed the time, location, duration and nature of activities intended to simulate daily activity patterns for adults and children. Scripts were paired such that one individual would proceed with usual activities (base scenario), whereas the other (intervention scenario) would alter activities as if following advice. Other than commuting, where the intervention group walked or used public transportation rather than riding in personal vehicles, this group generally spent less time outdoors. Ultra-fine particles (UFPs), particulate matter of median aerodynamic diameter less than 2.5 m (PM_2.5) and total volatile organic compounds (VOCs) were measured using samplers carried by individuals during the course of daily activities. During daytime activities (e.g., work, daycare) constituting the largest share of sampling time (approximately 6 h per day), the intervention group experienced a 14% reduction in exposure to UFPs (P=0.01), a 21% reduction in exposure to PM_2.5 (P=0.08), and an 86% increase in exposure to VOCs (P=0.02). Other findings included an 89% increase in exposure to UFPs (P=0.02) and a threefold increase in exposure to VOCs (P=0.08) in the intervention group during evening cooking. Following smog advisory advice results in reduced exposures to some pollutants, while at the same time increasing exposure to others. Advice needs to be refined giving consideration to overall personal exposure.