STUDY ON CARBONACEOUS SPECIES AND HEAVY METALS DURING AN EPISODIC POLLUTION EVENT IN DELHI, INDIA

Abstract

Ambient respirable fraction was sampled for a seven day special observation period during the festival of lights- Diwali, in a residential area, Delhi, India. Every year this “festival of lights” releases toxic chemical species in the air degrading the quality of air. In recent years, carbonaceous fraction of particulate matter has gained large interest due to its significance in altering the air quality adversely and climate patterns. Delhi, the capital city of India, already reeling under the criticism of being in top rankings of world’s most polluted cities is making staggering efforts to abate its air pollution. With such a title thrust to it, such an episodic pollution due to Diwali festivities in the winter months when the temperature and mixing heights are low, forces air quality to reach a new ebb. Among the analyzed species, Organic Carbon(OC) contributed to ~28% and Elemental Carbon (EC) ~14% with an increase in concentration by a factor of 2.27 and 2.02 times on Diwali day than the previous day. Although, contributions of secondary organic aerosols has not been investigated in this study, higher OC/EC ratio following after the days of Diwali suggests its contribution to OC concentration. Nine heavy metals (Al, Cr, Cu, Ba, Zn, Fe, Pb, Mn and Ni) also commensurate to PM5 loadings. Fe, Pb, Cu and Mn hint their more use in the manufacture of firecrackers with seemingly less use of Zn, Ba and Al this time. The non-carcinogenic and carcinogenic risks due to short episodic pollution of Diwali has also been accounted. An increase of Hazard Index (HI) by~8% manifests the severity of Diwali metal pollution.