Research | Children’s Health Personal Exposures to Traffic-Related Air Pollution and Acute Respiratory Health among Bronx Schoolchildren with Asthma Ariel Spira-Cohen,1 Lung Chi Chen,1 Michaela Kendall,2 Ramona Lall,1 and George D. Thurston1 1Nelson Institute of Environmental Medicine, New York University School of Medicine, Tuxedo, New York, USA; 2European Centre for Environment and Human Health, Peninsula College of Medicine and Dentistry, University of Exeter, The Knowledge Spa, Truro, Cornwall, United Kingdom Boundackgr : Previous studies have reported relationships between adverse respiratory health out- comes and residential proximity to traffic pollution, but have not shown this at a personal exposure level. o Bjectiv : We compared, among inner-city children with asthma, the associations of adverse asthma outcome incidences with increased personal exposure to particulate matter mass ≤ 2.5 mμ in aerodynamic diameter (PM2.5) air pollution versus the diesel-related carbonaceous fraction of PM2.5. Methods : Daily 24-hr personal samples of PM2.5, including the elemental carbon (EC) fraction, were collected for 40 fifth-grade children with asthma at four South Bronx schools (10 children per school) during approximately 1 month each. Spirometry and symptom scores were recorded several times daily during weekdays. r esult : We found elevated same-day relative risks of wheeze [1.45; 95% confidence interval (CI), 1.03–2.04)], shortness of breath (1.41; 95% CI, 1.01–1.99), and total symptoms (1.30; 95% CI, 1.04–1.62) with an increase in personal EC, but not with personal PM2.5 mass. We found increased risk of cough, wheeze, and total symptoms with increased 1-day lag and 2-day average personal and school-site EC. We found no significant associations with school-site PM2.5 mass or sulfur. The EC effect estimate was robust to addition of gaseous pollutants. c onclusi : Adverse health associations were strongest with personal measures of EC exposure, suggesting that the diesel “soot” fraction of PM2.5 is most responsible for pollution-related asthma exacerbations among children living near roadways. Studies that rely on exposure to PM mass may underestimate PM health impacts. k ye dswor : air pollution, asthma, children’s health, diesel, elemental carbon, personal monitoring traffic, PM2.5. Environ Health Perspect 119:559–565 (2011). doi:10.1289/ehp.1002653 [Online 7 January 2011] Adverse respiratory health outcomes in published traffic proximity–exposure stud- ies include increased prevalence of asthma (McConnell et al. 2006; Nicolai et al. 2003), wheezing (Gauderman et al. 2005; Nordling et al. 2008), recurrent respiratory illnesses (Kim et al. 2004), decreased lung function (Balmes et al. 2009; Brunekreef et al. 1997; Kan et al. 2007), increased lung inflamma- tion markers (Dales et al. 2008; Holguin et al. 2007), and increased medical visits and hospi- tal admissions for asthma (Chang et al. 2008; English et al. 1999). Increased immuno- globulin E (IgE) production from controlled exposure to diesel exhaust particles (DEP) (Diaz-Sanchez et al. 1997) provides mecha- nistic support for the role of DEP in the asso- ciations of adverse respiratory health with traffic indicators. The presence of elemental carbon (EC) in the lung has also been directly associated with adverse effects (Kulkarni et al. 2006), and increased EC concentrations have been associated with increased exhaled nitric oxide—a marker of airway inflamma- tion (Delfino et al. 2006)—supporting the hypothesis that it is exposure to DEP that causes the associations of traffic with asthma exacerbations. Personal measurements of vehicle-related particle exposures and acute respiratory health outcomes are currently lacking in most studies of this issue. Bronx County has among the highest incidences of asthma emergency department (ED) visits and hospital discharges both in New York City (NYC) and throughout New York State (New York State Department of Health 2009). The South Bronx area of Bronx County is particularly affected, with children’s asthma hospitalization rates several times higher in the South Bronx than in other NYC areas (Claudio et al. 2006). The South Bronx provides an ideal context in which to investigate the effects of traffic-related air pol- lution on children with asthma because large numbers of children with asthma live and attend schools in close proximity to highways and businesses that rely on high volumes of truck traffic. Large volumes of heavy truck traffic pass through the South Bronx along several major highways, as well as to and from a quarter of NYC’s waste transfer facilities (Naphtali et al. 2007), the Bronx Terminal, and Hunts Point wholesale fish, flower, and produce markets. Although EC is not a unique marker for DEP exposure in all cases, our previous expo- sure assessment work in the study area has shown that EC concentrations are a reliable Environmental Health Perspectives • volume 119 | number 4 | April 2011 indicator of truck traffic–generated pollution in this inner-city locale, for which we found evidence that > 90% of the Bronx EC can come from diesel exhaust (Spira-Cohen et al. 2010). New York University’s (NYU) prior exposure assessment work in the study area (Maciejczyk et al. 2004) also showed that variations in ground-level BC concentrations in the South Bronx were related to local truck traffic density. Although levels of other pollutants have shown a significant decline in NYC in the last decade, EC levels have not shown the same decline (Narvaez et al. 2008). In the previ- ously published exposure assessment findings of this study, we found that children living closer to a highway had progressively higher mean personal EC exposures and that con- centrations of EC varied with hourly truck traffic measurements near the most heavily trafficked school sampling site (Spira-Cohen et al. 2010). By collecting personal moni- toring data from a group of children with asthma in the South Bronx, in this analysis we are able to directly compare the health effects from exposure to particulate matter ≤ 2.5 µm in aerodynamic diameter (PM2.5) versus the diesel “soot” EC-related fraction of PM2.5. We therefore hypothesized that associations of adverse respiratory health effects with the Address correspondence to G.D. Thurston, Nelson Institute of Environmental Medicine, NYU School of Medicine, 57 Old Forge Rd., Tuxedo, NY 10987- 5007 USA. Telephone: (845) 731-3564. Fax: (845) 351-5472. E-mail: george.thurston@nyu.edu Supplemental Material is available online (doi:10.1289/ehp.1002653 via http://dx.doi.org/). The collaboration of the New York City School System and South Bronx community group partners (Youth Ministries for Peace and Justice, the Sports Foundation, Nos Quedamos, the Point CDC) was essential to the completion of this research. Special acknowledgment is owed to D. Xillari, J. Clemente, M. Blaustein, and J. Gorzcynski, who made signifi- cant contributions to this research. This work is supported by the Health Effects Institute, by New York University–National Institute of Environmental Health Sciences Center of Excellence grant 5P30ES000260, and by the U.S. Environmental Protection Agency (EPA) under grant R827351 (agreement X-982152) and under the Science to Achieve Results graduate fellowship program. The views expressed herein may not reflect the views of the U.S. EPA. The authors declare they have no actual or potential competing financial interests. Received 30 June 2010; accepted 7 January 2011. 559