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Ozone in ambient air at a tropical megacity, Delhi: Characteristics, trends and cumulative ozone exposure indices

Ghude, SD and Jain, SL and Arya, BC and Beig, G and Ahammed, YN and Kumar, A and Tyagi, B (2008) Ozone in ambient air at a tropical megacity, Delhi: Characteristics, trends and cumulative ozone exposure indices. Journal of Atmospheric Chemistry, 60 (3). pp. 237-252.

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Abstract

Seven year data of hourly surface ozone concentration is analyzed to study diurnal cycle, trends, excess of ozone levels above threshold value and cumulative ozone exposure indices at a tropical megacity, Delhi. The ozone levels clearly exhibit a diurnal cycle, similar to what has been found in other urban places. A sharp increase in the ozone levels during forenoon and a sharp decrease in the early afternoon can be observed. The average rate of increase in ozone concentration between 09 and 12 h has been observed to be 7.1 ppb h -1. We find that the daily maximum and daytime 8-h (10-17 h) ozone levels are increasing at a rate of about 1.7 (± 0.7) and 1.3 (± 0.56) ppb y-1, respectively. The directives on ozone pollution in ambient air provided by United Nations Economic Commission for Europe and World Health Organization for vegetation (AOT40) and human health protection were used to assess the air quality. The present surface ozone levels in the city are high enough to exceed "Critical Levels" which are considered to be safe for human health, vegetation and forest. The human health threshold was exceeded for up to ~45 days per year. The AOT40 (Accumulated exposure Over a Threshold of 40 ppb) threshold was exceeded significantly during winter (D-J-F) and pre-monsoon (M-A-M) (Rabi crop growing season) season in India. Translating AOT40 exceedances during pre-monsoon into relative yield loss we estimate yield loss of 22.7, 22.5, 16.3 and 5.5 for wheat, cotton, soybean and rice, respectively. © 2009 Springer Science+Business Media B.V.

Item Type: Article
Additional Information: Copyright of this article belongs to Springer
Uncontrolled Keywords: ozone, air quality; ambient air; atmospheric pollution; catch crop; diurnal variation; health impact; megacity; monsoon; ozone; pollution exposure; threshold; yield response, air pollution; air quality; ambient air; article; concentration (parameters); cotton; environmental exposure; forest; India; maximum allowable concentration; nonhuman; rice; soybean; time; tropic climate; urban area; vegetation; wheat; winter, Delhi; India, Glycine max; Gossypium hirsutum; Triticum aestivum
Subjects: Meteorology and Climatology
Depositing User: IITM Library
Date Deposited: 19 Feb 2015 04:47
Last Modified: 19 Feb 2015 04:47
URI: http://moeseprints.incois.gov.in/id/eprint/1841

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