Delhi, Meerut, Ludhiana, Agra, Kolkata, Patna, Lucknow, Kanpur, Mumbai, Asansol, Allahabad, Amritsar, Varanasi, Dhandbad, Jaipur, Jamshedpur, Surat and Bhbaneswar. It may be noted that annual PM2.5 concentration in many big urban areas (e.g. Bangalore, Chennai) is lower than that in rural areas in the Indo-Gangetic Basin. The episodic nature of such high particulate pollution has also been examined. Daily PM2.5 exceeding the World Health Organization interim target of 75 μg m-3 (which has potentially 5% higher short-term mortality risk relative to exposure to clean air with annual PM2.5 less than 25 μg m-3) in 40-50% of the clear days in the Indo-Gangetic Basin and Mumbai metropolitan area. If the lower interim target (37.5 μg m-3, Fig. 1b) is considered, frequency occurrence of daily PM2.5 exceeding the level is observed to be >75% of the time in a year. This suggests that the enormous pollution in these areas is rather persistent and thus bears more critical health implications. Five major hotspots (where PM2.5 has increased by >15 μg m-3 in the last decade) were identified in the analysis (left cover photo). These are western Indo-Gangetic Basin (H1), parts of rural areas of Bihar and West Bengal (H2), parts of Orissa and Chhattisgarh (H3), industrial belt in Gujarat and Maharashtra (H4) and industrial belt surrounding Hyderabad (H5).
The first regional scale analysis of PM2.5 over India has revealed many interesting facts and further emphasized on the following key issues that remain to be resolved:
- generation of a health database and cohort studies at the five hotspots shown above to establish exposure-response function for India
- examination of composition of PM2.5 at these hotspots, because health impacts of particles strongly depends on the composition
References
- Dey, S., L. Di Girolamo, A. Van Donkelaar, S. N. Tripathi, T. Gupta and M. Mohan (2012), Variability of outdoor fine particulate (PM2.5) concentration in the Indian Subcontinent: A remote sensing approach, Rem. Sens. Environ., 127, 153-161.
- Dey, S. and L. Di Girolamo (2010), A climatology of aerosol optical and microphysical properties over the Indian Subcontinent from 9 years (2000-2009) of MISR data, J. Geophys. Res., 115, D15204.
Dr. Sagnik Dey
IIT Delhi;
E-Mail: sagnik@cas.iitd.ac.in
