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Near-Surface Vertical Profiles of Urban Roadside NOx and Fine Particles

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Volume: 14 | Issue: 6 | Pages: 1763-1768
DOI: 10.4209/aaqr.2013.08.0278
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Yoshihiro Nakashima 1, Charlotte E. Jones2, Wakana Yamanobe3, Yoshizumi Kajii2

  • 1 Faculty of Agriculture, Tokyo University of Agriculture and Technology, 3-8-1 Harumi-cho, Fuchu, Tokyo, Japan
  • 2 Graduate School of Global Environmental Studies, Kyoto University, Yoshida-Honmachi, Sakyo-ku, Kyoto, Japan
  • 3 Aprica Children’s Products Japan Co. Ltd, 2-6-12 Ginza, Chuo-ku, Tokyo, Japan

Highlights

Height dependence of the concentration of NOx and fine particles near a major road in urban Tokyo was measured.

No significant height dependence was observed in the NOx concentration.

Number concentration of particles under 0.5 µm diameter demonstrated an exponential decrease with increasing height above ground level.

Fine particle concentration at 0.5 m above ground level was about 2.9 times higher than that at 2.0 m.

This result implies the risk of experiencing pollutant-related respiratory symptoms of children.


Abstract

This paper presents daytime vertical profiles of the NOx concentration, and the number concentration and size distribution of fine particles near a major road in urban Tokyo during spring 2011. No significant height dependence was observed in the NOx concentration, presumably due to rapid diffusion. In contrast, the number concentration of particles under 0.5 µm diameter demonstrated an exponential decrease with increasing height above ground level. Vertical profiles derived from this study differ from those presented in previous studies, however, these differences may potentially be explained by the different tailpipe positions of Japanese and US heavy vehicles, as well as the meteorological conditions. This study demonstrates that in Tokyo, the fine particle concentration at 0.5 m above ground level was about 2.9 times higher than that at 2.0 m. The higher fine particle concentration immediately above ground level implies that children may be at greater risk of experiencing pollutant-related respiratory symptoms than adults.

Keywords

Vertical concentration profile High density traffic road in urban area Fine particle


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