Emissions of Polycyclic Aromatic Hydrocarbons in the Atmosphere: An Indian Perspective

ABSTRACT

Organic compounds form a major fraction of airborne particles in the atmosphere and hence it is important to measure and identify them, especially the proportion of Polycyclic (Polynuclear) Aromatic Hydrocarbons (PAHs). The control and abatement of PAHs contamination requires the knowledge of the nature, source, and extent of pollution and hence existing literature on Indian studies was reviewed to gather information on the sources and emission rates of PAHs. Based on the results of the present study along with the data available from literature for particular PAHs in the ambient atmosphere, the vehicular and residential sector was identified as a major source of PAHs emission in many major Indian cities including Ahmedabad, Agra, Delhi, Kanpur, Lucknow, Mumbai, and Nagpur. Emissions of total PAHs range from 23–190 ng/m³, 369–1067 ng/m³, 20.8–100.8 ng/m³, and 12.7–206.4 μg/m³ from gasoline, diesel, petroleum refinery, and biomass, respectively, although it is recognized that this will vary from location to location. Additionally, the regulation and control of PAHs emission, and air quality standards for PAHs were also examined. Based on the toxicity assessment, the study highlights the need to include not only benzo[a]pyrene but also other probable human carcinogenic PAHs while developing a new air quality index for India.

Key Words:

• PAHs
• biomass fuels
• emission factors
• air quality standards
• PAH diagnostic ratio
• Toxic Equivalency Factors

ACKNOWLEDGMENTS

The authors are thankful to Prof. D.K. Bandhopadhyay, Vice Chancellor, GGS Indraprastha University, Prof. Nupur Prakash, Principal, IGIT and Prof. R.C. Budhani, Director, NPL for their encouragement and support. The authors also thank CSIR for the award of Research Project and SRF to one of the authors (DPS) under the project.