What is the status of air pollution in Delhi?

Delhi has lost the gains of its CNG programme. Its air is increasingly becoming more polluted and unbreathable, bringing back the pre-CNG days when diesel-driven buses and autos had made it one of the most polluted cities on earth.

In 2001, when the CNG programme was on, the annual average level of respirable suspended particulate matter (RSPM, or PM10) in residential areas stood at 149 microgram per cubic metre. After registering a drop in 2005, the level has shot up to 209 microgram per cubic metre in 2008. The concentration is, thus, around three times higher than the safe levels.

Eight-hourly maximum current level of carbon monoxide (CO) is touching 6,000 microgram per cubic metre – way above the safe level of 2,000 microgram per cubic metre – though the annual levels have registered a drop.

Levels of nitrogen dioxide (NO2), though lower than the standard in most areas as yet, have also been increasing marginally (especially at the Town Hall, Chandni Chowk, monitoring point of the CPCB).

In the past five years, the city has done all it can to reduce pollution. It has advanced emission norms of vehicles; strengthened its ‘pollution under control’ system with new equipment; capped the number of its autorickshaws; converted buses to CNG; made it mandatory for new light commercial vehicles to run on CNG; and restricted commercial vehicles from entering the city.

But in spite of all these actions, pollution levels are on the rise. Delhi has more than four million registered vehicles. Currently, the city adds over 1,000 new personal vehicles each day on its roads. This is almost double what was added in the city in pre-CNG days. And a considerable number of these vehicles run on diesel.

According to the Society for Indian Automobile Manufacturers (SIAM), market share of diesel cars is expected to be 50 per cent of total car sales by 2010. This growth in personal diesel vehicle numbers will undo all the efforts to reduce pollution by phasing out diesel buses and converting them to CNG. According to CSE’s estimates, the total number of diesel cars presently in Delhi is equivalent to adding particulate emissions from nearly 30,000 diesel buses.

Diesel vehicles are known to emit higher smoke, particles and NOx than their petrol counterparts. According to WHO and other international regulatory and scientific agencies, diesel particulates are carcinogens. Even the so-called ‘clean’ diesel running on fuel with 350 ppm of sulphur, allows higher limits for NOx and particulate emissions compared to petrol cars.

The most worrying trend is a decreasing ridership of Delhi’s buses – according to a 2008 study done by RITES, between 2001 to 2007-08, the bus’s share in the modal split has fallen from 60 per cent to 41 per cent.