The influence of neighborhood traffic density on the respiratory health of elementary schoolchildren Sabit Cakmak a, 1 , Mamun Mahmud b, 2 , Alice Grgicak-Mannion c, 3 , Robert E. Dales d, ⁎ a Air Health Effects Research Section, Population Studies Division, Environmental Health Science & Research Bureau, Health Canada, 50 Columbine Driveway, Ottawa, ON, Canada K1A 0K9 b Biostatistics Section, Population Studies Division, Environmental Health Science & Research Bureau, Health Canada, Ottawa, ON, Canada K1A 0K9 c Great Lakes Institute for Environmental Research University of Windsor, 401 Sunset Ave., Windsor, ON, Canada N9B 3P4 d Health Canada, Professor of Medicine, University of Ottawa Departments of Medicine and Epidemiology, Clinician-Scientist, Ottawa Hospital Research Institute, The Ottawa Hospital (General Campus), 501 Smyth Road, Box 211, Ottawa, ON, Canada K1H 8L6 abstract article info Article history: Received 29 March 2011 Accepted 17 October 2011 Available online 18 November 2011 Keywords: Traffic Air pollution Environment Exhaled nitric oxide Respiratory system Spirometry Background: Several studies have found that living near major roadways is associated with an increase in re- spiratory illness but few studies have measured the volume and type of traffic. Objective: We investigated the relation between traffic volume and respiratory health of 2328 children 9 to 11 years old in the city of Windsor, Canada. Methods: We identified the roadways within a 200 meter radius of the child's neighborhood using the latitude and longitude of the residential postal code. Traffic exposure was defined as the sum of the annual volume of vehicles on all of these roadways. Volume was calculated using sensors to detect passing vehicles (simple traffic counts), and by counts and direction of traffic at intersections (turning movement counts). Ventilatory lung function was measured by spirometry and airway inflammation by exhaled nitric oxide (eNO). Results: The odds ratio between an interquartile increase in truck turning movement counts and chest congestion was 1.20 (1.06–1.35). The percentage of predicted FVC declined 0.68%, (95% CI 1.32, 0.03) for an interquartile in- crease in simple traffic counts (33,787 vehicles daily). Among those with self-reported asthma, effect sizes were larger. Percentage predicted FEV 1 declined 1.84% (95% CI 0.07, 3.61) associated with an interquartile range in- crease in turning movement counts. No statistically significant change was detected between traffic measures and exhaled nitric oxide. Conclusions: Our findings provide further support for the hypothesis that neighborhood exposure to traffic-related air pollution increases respiratory symptoms and reduces ventilatory function in children, especially those with self-reported asthma. © 2011 Elsevier Ltd. All rights reserved. 1. Introduction Exposure to traffic-related air pollution, often indicated by prox- imity of home or school to a major roadway, ambient nitrogen dioxide (NO 2 ) or fine particulate air pollution (PM 2.5 ) has been associated with increased reports of wheeze and asthma in children in some, but not all, studies (Heinrich and Wichmann, 2004; Janssen et al., 2003; Kim et al., 2004; Lin et al., 2002). A review of the literature by The Health Effects Institute published in January of 2010 concluded that the evidence was insufficient to infer the presence of a causal as- sociation between traffic-related air pollution and cardiovascular morbidity, respiratory symptoms in those without asthma, and changes in lung function (The Health Effects Institute, www. healtheffects.org). We previously reported that each kilometer of any type of roadway within 200 m of the subjects neighborhood was associated with wheeze, wheeze and asthma and an increase in exhaled nitric oxide (NO), a measure of airway inflammation in asth- ma (Dales et al., 2008, 2009). We found no significant reduction in ventilatory lung function assessed by one-second forced expired vol- ume (FEV 1 ) and forced vital capacity (FVC). The present study is a re-analysis of our data using a different metric of traffic exposure. In addition to the total length of all roadways surrounding the neighbor- hood, we now have available an estimate of the total traffic counts on these roadways. Environment International 39 (2012) 128–132 Abbreviations: TMC, Turning movement counts; FEV 1 , Forced expired volume; FVC, Forced vital capacity; eNO, Exhaled nitric oxide; SO 2 , Sulfur dioxide; NO 2 , Nitrogen di- oxide; PM 2.5 , Fine particulate matter; SE, Standard error. ⁎ Corresponding author at: The Ottawa Hospital (General Campus), 501 Smyth Road, Box 211, Ottawa, Ontario, Canada K1H 8L6. Tel.: +1 613 737 8198; fax: +1 613 737 8537. E-mail addresses: sabit_cakmak@hc-sc.gc.ca (S. Cakmak), mamun.mahmud@hc-sc.gc.ca (M. Mahmud), grgica3@uwindsor.ca (A. Grgicak-Mannion), rdales@ohri.ca (R.E. Dales). 1 Tel.: +1 613 952 6913; fax: +1 613 941 3883. 2 Tel.: +1 613 948 6140; fax: +1 613 954 7612. 3 Tel.: +1 519 253 3000x2170; fax: +1 519 971 3616. 0160-4120/$ – see front matter © 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.envint.2011.10.006 Contents lists available at SciVerse ScienceDirect Environment International journal homepage: www.elsevier.com/locate/envint