Industries and power plants in and around Delhi are the biggest source of pollutants, SO2 and NOx, that cause breathing ailments in the city. A study by the Indian Institute of Technology (IIT) Kanpur revealed that power plants, industrial clusters, restaurants and the diesel generators are the primary source of pollution from sulfur dioxide (SO2) and nitrogen oxides (NOx). Nine months have passed since the findings but nothing has been done to implement the recommendations to control pollution from industrial sources.
As per the study, almost 98% of the 142 tonne SO2 and 60 per cent of the 312 tonne NOx emitted in Delhi’s air every day, comes from these sources. Breathing SO or NOx for short periods can cause adverse respiratory effects such as airway inflammation, bronchoconstriction and asthma symptoms. The pollutants also harm health by reacting in the atmosphere to form sulphate or nitrate fine particles, PM2.5, that chock airways to lungs.
Apart from SO2 and NOx, these sources also directly contribute close to 19% of the PM2.5 and 14% of PM10 levels in the city.
In the past few months, the government has taken some immediate measures to control pollution from vehicles and farm fires, however, it has shied away from implementing long-term measures. “We have implemented measures such as total control on garbage burning in the city and cleaning of road dust but coordinating other measures to control industrial pollution will take time. We need to think of the alternatives first,” said a senior official in the Delhi Pollution Control Committee (DPCC) who did not wish to be named.
How industries pollute Delhi
Several small and medium-size industries were relocated from Delhi in the 1990s as a measure to control pollution but that has not been enough. The city has two power plants — at Rajghat and Badarpur — and about 20 big industries (having stack height more than 20m) which contribute more than 90% to the SO2 and more than half to the NOx emissions, the IIT Kanpur study says.
The two power plants are also major sources of fly-ash. Officials in the environment department of the Delhi government asserted that they have implemented strict measures to control fly-ash. However, they admit that fly-ash from poorly-maintained disposal ponds becomes a problem in summers. Coal and fly-ash contribute about 30% of PM10 in summers, the study said.
The city also has about 25 industrial clusters, many in close proximity to residential areas, emitting more than 5.6tonne of SO2, 1.9tonne of NOx, 1.4tonne of PM2.5 and 1.6tonne of PM10 per day, the study says. “Many of these industrial units use low quality fuel, including furnace oil, illegally. This causes more pollution,” said Bhure Lal, chairman of the Environment Pollution (Prevention and Control) Authority (EPCA). While the government has banned use of oil with over 500ppm sulphur content in the city, Lal said the government has not conducted any inspections to check if the industries are violating the fuel norms.
Tandoor and DG sets
The DPCC records show there are about 9,000 hotels and restaurants in the city which use coal, mostly for tandoors. They contribute about 3.5tonne of PM10, 1.8tonne of PM2.5 and 2.7tonne of SO2 in Delhi per day and are a major source of fly-ash, the IIT Kanpur study said. It recommended that restaurants with a sitting capacity of more than ten should not use coal and shift to electric or gas-based appliances.
Besides, diesel generator (DG) sets are significant contributors to the pollution. As per the study, close to 20tonne of NOx (6% of the total NOx) is produced by DG sets in the city per day. There is a minimum two-hour power cut in the city per day, especially during summer and the use of DG sets is common in shopping complexes and industrial units. The study recommended that all DG sets of size 2KVA, or less, should not be allowed to operate; fuel of more than 500PPM sulphur content should be checked and solar powered generation, storage and inverter should be promoted.
An official in the DPCC said the measures were not practical. “Tandoors are a part of Delhi’s food culture. Why would the restaurants want to move away from it? Do we have a better alternative? Also, it is not possible to inspect each and every DG sets. The only solution to from DG sets is uninterrupted power supply,” he added.
The study also said that there were at least 13 thermal power plants (TPP) with a capacity of over 11,000MW within a radius of 300km of Delhi, which contribute majorly to secondary particles. Secondary particles, formed from chemical transformation of SO2 and NOx gases, have been the most consistent sources of PM2.5 and PM10 levels in Delhi both in summer and winters. As per the study, the North-West winds transport SO2 emitted from large power plants and refineries in the upwind of Delhi and transform it into sulfates.
“What is more worrying is that nine more coal-fired power plants are under construction and 36 units are in the pipeline within 500km radius of Delhi. Our satellite-based analysis revealed that there is a direct co-relation between increase in coal consumption and increase in SO2 and NOx levels in the NCR,” said Nandikesh Sivalingam of Greenpeace India.
The IIT study recommended that de-SOx-ing and de-NOx-ing — processes of removing SO2 and NOx through chemical reactions at the production stage — at all power plants within 300km of Delhi should be carried out. This could reduce PM10 concentration approximately by 99 microgram per cubic meter (µg/m3) and PM2.5 concentration by 57 µg/m3, the study said. The government has not taken any step in this direction yet, officials in the environment department told HT.
This is the concluding part of ‘Save our lungs’ series, which examined air pollution in Delhi.