|Monthly average of PM10 and NO2 in winter months of Sept to Feb during 1998-2006. Since 2004, the data shows an upward trend. Click to enlarge.|
A new assessment by India’s Centre for Science and Environment (CSE) of the trends in the peak pollution levels of Delhi during winter months since 1998 has found that pollution in winter—despite a decrease until 2003—has begun to rise once again.
CSE attributes the rising pollution to the rapid growth in cars—especially diesel cars—in the city. Over the last 10 years, the total personal vehicle registration has increased 105%; cars alone have increased by 157% and diesel cars have increased by 425%.
Diesel cars in 2006 represent nearly 20% of new car registrations in Delhi, up from 4% in 1999. While gasoline cars have increased at 8.5% annually, diesel cars have maintained a growth rate of 16.6%.
The cumulative effect is overwhelming the emissions benefits gained by the city’s earlier phase-out of its 12,000 diesel buses. CSE calculates that the 118,631 diesel cars on the city’s roads are equivalent to adding particulate emissions from nearly 30,000 diesel buses.
Diesel is making a comeback through personal transport and is threatening to nullify the impact of the CNG programme. Officials warn that the number of bigger jeeps or SUVs, taken separately, could be much higher due to their daily influx from the surrounding satellite towns. A large number of these vehicles come to Delhi and leave the city during peak hours. Diesel cars and SUVs not only emit several times more particulates, but are also allowed to emit three times more NOx compared to a petrol car. Even the assessment of trends in fuel consumption in the city confirms that the total diesel fuel consumption that was lowered with the ascendancy of CNG in the beginning of this decade has begun to increase again.—CSE
Delhi tackled its earlier pollution problem by implementing one of the largest CNG programs in the world, implementing Euro-2 and Euro-3 standards, reducing the sulfur content of fuel to 500 ppm and subsequently to 350 ppm, lowering benzene to 1% and capping the age of commercial vehicles at 15 years.
These first-generation mitigation efforts helped to stabilize particulates and substantially lower SO2 and CO. Substantial air quality gains were made possible with aggressive measures. However, CSE notes, particulate levels, despite stabilization, are still very high and NOx levels are steadily rising.
CSE is urging that Delhi take measures this winter to mitigate pollution, including:
Initiate stringent on road checks for smoky vehicles. Harsh penalties should be imposed if vehicles are seen with visible smoke.
Supportive measures are needed to intensify use of public transport this winter. Buses already meet as much as 61% of the travel demand in Delhi. Cars and two-wheelers take up nearly 90% of the road space, but meet less than 20% of travel demand. Services of both metro and the existing bus system should be intensified to encourage maximum usage.
Intensify dedicated bus and railway services between Delhi and the surrounding satellite towns to discourage commuting in cars.
Encourage alternative-fuelled cars and discourage polluting cars, particularly on very high pollution days or in high pollution zones to be identified from the CPCB’s air pollution data.