@article{25590,
  keywords = {exposure, particulate matter, microenvironment, transportation, Megacity, Urban air quality},
  author = {Joshua S Apte and Thomas W Kirchstetter and Alexander H Reich and Shyam J Deshpande and Geetanjali Kaushik and Arvind Chel and Julian D Marshall and William W Nazaroff},
  title = {Concentrations of fine, ultrafine, and black carbon particles in auto-rickshaws in New Delhi, India},
  abstract = {<p>Concentrations of air pollutants from vehicles are elevated along roadways, indicating that human exposure in transportation microenvironments may not be adequately characterized by centrally located monitors. We report results from ∼180 h of real-time measurements of fine particle and black carbon mass concentration (PM<sub>2.5</sub>, BC) and ultrafine particle number concentration (PN) inside a common vehicle, the auto-rickshaw, in New Delhi, India. Measured exposure concentrations are much higher in this study (geometric mean for ∼60 trip-averaged concentrations: 190 μg m<sup>−3</sup> PM<sub>2.5</sub>, 42 μg m<sup>−3</sup> BC, 280 × 10<sup>3</sup> particles cm<sup>−3</sup>; GSD ∼1.3 for all three pollutants) than reported for transportation microenvironments in other megacities. In-vehicle concentrations exceeded simultaneously measured ambient levels by 1.5× for PM<sub>2.5</sub>, 3.6× for BC, and 8.4× for PN. Short-duration peak concentrations (averaging time: 10 s), attributable to exhaust plumes of nearby vehicles, were greater than 300 μg m<sup>−3</sup> for PM<sub>2.5</sub>, 85 μg m<sup>−3</sup> for BC, and 650 × 10<sup>3</sup> particles cm<sup>−3</sup> for PN. The incremental increase of within-vehicle concentration above ambient levels—which we attribute to in- and near-roadway emission sources—accounted for 30%, 68% and 86% of time-averaged in-vehicle PM<sub>2.5</sub>, BC and PN concentrations, respectively. Based on these results, we estimate that one's exposure during a daily commute by auto-rickshaw in Delhi is as least as large as full-day exposures experienced by urban residents of many high-income countries. This study illuminates an environmental health concern that may be common in many populous, low-income cities.</p>},
  year = {2011},
  journal = {Atmospheric Environment},
  volume = {45},
  pages = {4470–4480},
  month = {05/2011},
  doi = {10.1016/j.atmosenv.2011.05.028},
}