A Photochemical Modelling Approach to Investigate O3 Sensitivity to NOx and VOCs in the Urban Atmosphere of Delhi

Received: May 31, 2008
Revised: May 31, 2008
Accepted: May 31, 2008
Download Citation: RIS|BibTeX|https://doi.org/10.4209/aaqr.2007.09.0037  

Cite this article:
Kumar, U., Prakash, A. and Jain, V.K. (2008). A Photochemical Modelling Approach to Investigate O3 Sensitivity to NOx and VOCs in the Urban Atmosphere of Delhi. Aerosol Air Qual. Res. 8: 147-159. https://doi.org/10.4209/aaqr.2007.09.0037

ABSTRACT

Ambient air pollutants data were used to evaluate whether O₃ formation at a specific site (Sirifort) in Delhi was limited by volatile organic compounds (VOCs) or oxides of nitrogen (NO_x). For this purpose, a photochemical model OZIPR (Ozone Isopleth Plotting Research) based on Lagrangian trajectory model was applied to 9 ozone episodes that occurred at Sirifort from August to October 2006. Emissions data were estimated using an area-source box model. The results show that the prediction for peak O₃ concentration agreed reasonably well with the observed data. O₃-isopleth plots clearly reveal that O₃ formation is more sensitive to VOC emissions for lower VOCs/NO_x ratio, while for higher VOCs/NO_x ratio, O₃ formation is more sensitive to NO_x emissions. However, for the purpose of practical O₃ control applications at the observation site, it is concluded that VOCs emissions should be reduced while keeping a lower VOCs/NO_x ratio.

Keywords: OZIPR; Photochemical modelling; Ozone; NOx; VOCs