Capital’s pollution woes | Over 1,500 polluting units shut in NCR: CAQM

These clusters are part of a larger industrial region, which affects Delhi’s air quality.

Delhi’s AQI remained in the ‘very poor’ category on Monday, with the 24-hour average settling at 351, a slight improvement from 377 recorded on Sunday, according to the CPCB.

In the affidavit filed in the Supreme Court, the CAQM also stated that out of about 50,000 operational industries across the Delhi-NCR, nearly 11,000 fall under the air-polluting category. These are units whose manufacturing processes, fuel use or emissions place them under the highest levels of regulatory scrutiny. They range from large industrial boilers and metal furnaces to smaller combustion-based units operating inside densely packed clusters around the capital.

The industrial sector’s share in Delhi’s PM2.5 appears modest when viewed within city limits. A Decision Support System (DSS) developed by the Indian Institute of Tropical Meteorology estimates that industry, construction and the energy sector together contribute around 10 per cent to Delhi’s particulate levels on most days. However, an assessment by the Centre for Science and Environment (CSE), based on DSS data for non-crop-burning periods, shows that emissions transported from the surrounding NCR districts — including major industrial belts — can contribute up to two-thirds of Delhi’s PM2.5.

Under the national framework, the CPCB classifies every industrial sector using a pollution index — a score that combines its potential to pollute air, water and based on its generation of hazardous waste. Sectors with high scores are placed in the ‘Red’ category, which CPCB describes as “highly polluting” and subject to the strictest emission standards and regulatory control. Lower scores place sectors in the ‘Orange’ and ‘Green’ categories, while units falling under the ‘White’ category are considered practically non-polluting.

An industrial unit is treated as polluting if it belongs to high-pollution category, runs fuel- or process-intensive operations, or fails to comply with the emission norms and consent conditions notified under the Air Act, the Water Act and the Environment (Protection) Act.

The CAQM’s rules for industries in the NCR focus mainly on two aspects: the fuels they use and the amount of PM they are allowed to release. A set of directions limits smoke from units that run on biomass or low-sulphur liquid fuels, capping their PM emissions at 80 milligrams per normal cubic metre — a standard that applies to boilers, dryers and metal-melting furnaces across the region. Another direction establishes a uniform fuel list for all four NCR states, under which coal and several high-sulphur oils are restricted for industrial use, while PNG, LPG, electricity, hydrogen and biofuels are listed as permissible fuels.

The Delhi Pollution Control Committee, in a report submitted to the National Green Tribunal on November 14, said it inspected 34 premises in the DSIIDC industrial areas of Narela and Bawana.

The CAQM affidavit also records that only some of the polluting industries in the NCR are covered by real-time emissions reporting.

“The current policy, which mandates OCEMS for 3,551 out of 11,000 polluting units in densely populated and heavily polluted areas, creates a massive enforcement blind spot,” said Sunil Dahiya, air-quality analyst and founder of Envirocatalysts. “In the absence of real-time emission data, we have no way to hold the majority of industries accountable during critical periods like GRAP or verify their compliance over time.”