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Open Access Research

A new exposure metric for traffic-related air pollution? An analysis of determinants of hopanes in settled indoor house dust

Hind Sbihi1*, Jeffrey R Brook2, Ryan W Allen3, Jason H Curran1, Sharon Dell4, Piush Mandhane5, James A Scott6, Malcolm R Sears7, Padmaja Subbarao4, Timothy K Takaro3, Stuart E Turvey8, Amanda J Wheeler9 and Michael Brauer1

Author Affiliations

1 School of Population and Public Health, University of British Columbia, 2206 East Mall, Vancouver, BC, Canada V6T 1Z3

2 Air Quality Research Division, Environment Canada, 4905 Dufferin Street, Toronto, Ontario, Canada M3H 5T4

3 Faculty of Health Sciences, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada V5A 1S6

4 Division of Respiratory Medicine, The Hospital for Sick Children, 555 University Avenue, Toronto, Ontario, Canada M5G 1X8

5 Department of Pediatrics, Faculty of Medicine and Dentistry, University of Alberta, WC Mackenzie Health Sciences Centre, Edmonton, Alberta T6G 2R7, Canada

6 Dalla Lana School of Public Health, University of Toronto, 155 College St, Toronto ON M5T 3M7, Canada

7 Department of Medicine, Faculty of Health Sciences, McMaster University, 1280 Main St W, Hamilton ON L8S 4K1, Canada

8 BC Children’s Hospital and Child & Family Research Institute, 950 West 28th Ave, Vancouver, BC, Canada V5Z 4H4

9 Air Health Science Division, Health Canada, 269 Laurier Avenue West, Ottawa, Ontario, Canada K1A 0K9

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Environmental Health 2013, 12:48  doi:10.1186/1476-069X-12-48

Published: 19 June 2013

Abstract

Background

Exposure to traffic-related air pollution (TRAP) can adversely impact health but epidemiologic studies are limited in their abilities to assess long-term exposures and incorporate variability in indoor pollutant infiltration.

Methods

In order to examine settled house dust levels of hopanes, engine lubricating oil byproducts found in vehicle exhaust, as a novel TRAP exposure measure, dust samples were collected from 171 homes in five Canadian cities and analyzed by gas chromatography–mass spectrometry. To evaluate source contributions, the relative abundance of the highest concentration hopane monomer in house dust was compared to that in outdoor air. Geographic variables related to TRAP emissions and outdoor NO2 concentrations from city-specific TRAP land use regression (LUR) models were calculated at each georeferenced residence location and assessed as predictors of variability in dust hopanes.

Results

Hopanes relative abundance in house dust and ambient air were significantly correlated (Pearson’s r=0.48, p<0.05), suggesting that dust hopanes likely result from traffic emissions. The proportion of variance in dust hopanes concentrations explained by LUR NO2 was less than 10% in Vancouver, Winnipeg and Toronto while the correlations in Edmonton and Windsor explained 20 to 40% of the variance. Modeling with household factors such as air conditioning and shoe removal along with geographic predictors related to TRAP generally increased the proportion of explained variability (10-80%) in measured indoor hopanes dust levels.

Conclusions

Hopanes can consistently be detected in house dust and may be a useful tracer of TRAP exposure if determinants of their spatiotemporal variability are well-characterized, and when home-specific factors are considered.

Keywords:
Air pollution; Dust; Exposure assessment; Hopanes; Land use regression; Traffic