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Advances in Meteorology
Volume 2013 (2013), Article ID 740453, 9 pages
http://dx.doi.org/10.1155/2013/740453
Research Article

Interannual and Intraseasonal Variability in Fine Mode Particles over Delhi: Influence of Meteorology

1Indian Institute of Tropical Meteorology (Branch), Prof Ramnath Vij Marg, New Delhi 110060, India
2Department of Environmental Engineering, P. E. S. College of Engineering, Mandya, Karnataka 571401, India
3Sharda University, Knowledge Park III, Greater Noida 201306, India

Received 23 May 2013; Revised 26 September 2013; Accepted 3 October 2013

Academic Editor: D. M. Chate

Copyright © 2013 S. Tiwari et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Fine mode particles (i.e., PM2.5) were collected at Delhi, India, for three consecutive years from January 2007 to December 2009 and were statistically analyzed. Daily mean mass concentration of PM2.5 was found to be 108.81 ± 75.5 μg m−3 ranged from 12 to 367.9 μg m−3, which is substantially higher than the Indian National Ambient Air Quality Standards (NAAQS). Among the measurements, ~69% of PM2.5 samples exceeded 24 h Indian NAAQS of PM2.5 level ( µg m−3); however, ~85% samples exceeded its annual level (40 µg m−3). Approximately 30% of PM2.5 mass was in the range of 40–80 μg m−3, indicating abundance of fine particles over Delhi. Intraseasonal variability of PM2.5 indicates highest mass concentration during postmonsoon (154.31 ± 81.62 μg m−3), followed by winter (150.81 ± 74.65 μg m−3), summer (70.86 ± 29.31 μg m−3), and monsoon (45.06 ± 18.40 μg m−3). In interannual variability, it was seen that in 2008, the fine mode particle was ~23% and ~36% higher as compared to 2007 and 2009, respectively. Significantly negative correlation was found between PM2.5 and temperature (−0.59) as well as wind speed (−0.38). Higher concentration of PM2.5 (173.8 μg m−3) was observed during calm conditions whereas low concentration (79.18 μg m−3) was observed when wind speed was >5 Km/hr. In winter, greater exposure risk is expected, as the pollutant often gets trapped in lower atmosphere due to stable atmospheric conditions.