title: Differences in Ambient Polycyclic Aromatic Hydrocarbon Concentrations between Streets and Alleys in New York City: Open Space vs. Semi-Closed Space.
abstract: BACKGROUND
  Outdoor ambient polycyclic aromatic hydrocarbon (PAH) concentrations are variable throughout an urban environment. However, little is known about how variation in semivolatile and nonvolatile PAHs related to the built environment (open space vs. semi-closed space) contributes to differences in concentrations.
  
  
  METHODS
  We simultaneously collected 14, two-week samples of PAHs from the outside of windows facing the front (adjacent to the street) open side of a New York City apartment building and the alley, semi-closed side of the same apartment unit between 2007 and 2012. We also analyzed samples of PAHs measured from 35 homes across Northern Manhattan and the Bronx, 17 from street facing windows with a median floor level of 4 (range 2-26) and 18 from alley-facing windows with a median floor level of 4 (range 1-15).
  
  
  RESULTS
  Levels of nonvolatile ambient PAHs were significantly higher when measured from a window adjacent to a street (an open space), compared to a window 30 feet away, adjacent to an alley (a semi-closed space) (street geometric mean (GM) 1.32 ng/m³, arithmetic mean ± standard deviation (AM ± SD) 1.61 ± 1.04 ng/m³; alley GM 1.10 ng/m³, AM ± SD 1.37 ± 0.94 ng/m³). In the neighborhood-wide comparison, nonvolatile PAHs were also significantly higher when measured adjacent to streets compared with adjacent to alley sides of apartment buildings (street GM 1.10 ng/m³, AM ± SD 1.46 ± 1.24 ng/m³; alley GM 0.61 ng/m³, AM ± SD 0.81 ± 0.80 ng/m³), but not semivolatile PAHs.
  
  
  CONCLUSIONS
  Ambient PAHs, nonvolatile PAHs in particular, are significantly higher when measured from a window adjacent to a street compared to a window adjacent to an alley, despite both locations being relatively close to street traffic. This study highlights small-scale spatial variations in ambient PAH concentrations that may be related to the built environment (open space vs. semi-closed space) from which the samples are measured, as well as the relative distance from street traffic, that could impact accurate personal exposure assessments.
authors.affiliation: Division of Pulmonology, Department of Pediatrics, College of Physicians and Surgeons, Columbia University, 3959 Broadway, CHC 7-724, New York, NY 10032, USA. sl3230@cumc.columbia.edu.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Lovinsky-Desir
authors.affiliation: Division of Pulmonary, Allergy and Critical Care of Medicine, Department of Medicine, College of Physicians and Surgeons, Columbia University, PH8E-101, 630 W. 168 St., New York, NY 10032, USA. rlm14@cumc.columbia.edu.|Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, 722 W. 168 St. New York, NY 10032, USA. rlm14@cumc.columbia.edu.|Division of Pediatric Allergy and Immunology, Department of Pediatrics, College of Physicians and Surgeons, Columbia University, PH8E-101, 630 W. 168 St. New York, NY 10032, USA. rlm14@cumc.columbia.edu.
authors.forename: Rachel L
authors.initials: RL
authors.lastname: Miller
authors.affiliation: Division of Pulmonary, Allergy and Critical Care of Medicine, Department of Medicine, College of Physicians and Surgeons, Columbia University, PH8E-101, 630 W. 168 St., New York, NY 10032, USA. jbb2160@cumc.columbia.edu.
authors.forename: Joshua
authors.initials: J
authors.lastname: Bautista
authors.affiliation: Division of Pulmonary, Allergy and Critical Care of Medicine, Department of Medicine, College of Physicians and Surgeons, Columbia University, PH8E-101, 630 W. 168 St., New York, NY 10032, USA. ericngil3@gmail.com.
authors.forename: Eric N
authors.initials: EN
authors.lastname: Gil
authors.affiliation: Lamont-Doherty Earth Observatory, Columbia University, 61 Rt., 9W Palisades, New York, NY 10964, USA. chilli@ldeo.columbia.edu.
authors.forename: Steven N
authors.initials: SN
authors.lastname: Chillrud
authors.affiliation: Lamont-Doherty Earth Observatory, Columbia University, 61 Rt., 9W Palisades, New York, NY 10964, USA. by2142@columbia.edu.
authors.forename: Beizhan
authors.initials: B
authors.lastname: Yan
authors.affiliation: Chemistry and Chemical Engineering Division, Southwest Research Institute, 6220 Culebra Road, San Antonio, TX 78228, USA. david.camann@swri.org.
authors.forename: David
authors.initials: D
authors.lastname: Camann
authors.affiliation: Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, 722 W. 168 St. New York, NY 10032, USA. fpp1@columbia.edu.
authors.forename: Frederica P
authors.initials: FP
authors.lastname: Perera
authors.affiliation: Division of Pulmonary, Allergy and Critical Care of Medicine, Department of Medicine, College of Physicians and Surgeons, Columbia University, PH8E-101, 630 W. 168 St., New York, NY 10032, USA. kj2237@cumc.columbia.edu.
authors.forename: Kyung Hwa
authors.initials: KH
authors.lastname: Jung
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D000397:Air Pollution / Q000032:analysis* / Q000706:statistics & numerical data; D002947:Cities; D004779:Environment Design; D004784:Environmental Monitoring; D009519:New York City; D011084:Polycyclic Aromatic Hydrocarbons / Q000032:analysis*
chemical_list: D000393:Air Pollutants; D011084:Polycyclic Aromatic Hydrocarbons
keywords: aged air; alley vs. street; ambient polycyclic aromatic hydrocarbons; built environment; open vs. semi-closed space; spatial variation