Delhi’s hotels and restaurants are the biggest contributors to air pollution in the national Capital, says finding of a study conducted by IIT-Kanpur on increasing levels of air pollution in Delhi. There are approximately 9,000 hotels/ restaurants in the city which use coal (mostly in tandoors) and the PM emission in the form of fly ash from this source is large, worsening city’s air quality. It is proposed that all restaurants with sitting capacity of more than 10 should shift to electric or gas-based appliances.
The second biggest polluter is domestic sector. Although Delhi is kerosene free and 90 per cent of the households use lPG for cooking, the remaining 10 per cent use wood, crop residue, cow dung, and coal for cooking (Census-India, 2012).
The vehicular pollution is also the largest source and most consistently contributing to rise in PM10 and PM2.5 in winters. “Various control options — including the implementation of BS VI, introduction of electric and hybrid vehicles, traffic planning and restriction of movement of vehicles, retro-fitment in diesel exhaust, improvement in public transport, etc — have been proposed and their effectiveness has been assessed,” said the IIT report.
Another major contributor to air pollution is Mass Solid Waste (MSW) burning. One of the reasons for burning MSW is lack of infrastructure for timely collection of MSW and it is conveniently burned or it may smolder slowly for a long time.
As per the report, infrastructure for collection and disposal (landfill and waste to energy plants) of MSW has to improve and burning of MSW should be banned completely.
The massive construction/demolition works in Delhi is also contributing to air pollution. Another polluter is ready mix concrete batching, used for construction activities.
The fifth biggest polluter is identified as coal and fly ash. In summer, coal and flyash contribute about 30 per cent of PM10 and unless sources contributing to flyash are controlled, one cannot expect significant improvement in air quality.
The soil and road dust is also contributor to air pollution. In winter, this source can contribute about 26 per cent to PM10 and PM2.5. The silt load on some of the Delhi’s road is very high and it can become airborne with the movement of vehicles. The estimated PM10 emission from road dust is over 65 tonnes per day.
Industries and Diesel Generator Sets also come in the list of major polluter. Several measures have been taken to control emissions in the industry (including relocation), especially in small and medium size industries, the report says.
Secondary particles, which are major contributors to PM level, are expected to source from precursor gases (SO2, and NOx) which are chemically transformed into particles in the atmosphere. Mostly the precursor gases are emitted from far distances from large sources. For sulfates, the major contribution can be attributed to large power plants and refineries. The Northwest wind is expected to transport SO2 and transform it into sulfates emitted from large power plants and refineries situated in the upwind of Delhi. However, NOx from local sources, especially vehicles and power plants, can also contribute to nitrates.
There are 13 thermal power plants (TPPs) with a capacity of over 11,000 MW in the radius of 300km of Delhi, which are expected to contribute to secondary particles.
Based on a study conducted in 2013, it was shown that power plants contribute nearly 80 per cent of sulfates and 50 per cent nitrates to the receptor concentration. A calculation assuming 90 per cent reduction in SO2 from these plants can reduce 72 per cent of sulphates, the report further states.