Global warming vs urban smog
The Centre for Science and Environment is shocked by the `expert’ views reported in the media that question the move to replace diesel with CNG, in the name of global warming. This is an attempt to divert attention from the more immediate problem of particulate pollution, which kills 1 person per hour in Delhi

Media is suddenly abuzz with reports carrying `expert’ views from industry consultancy groups that moving buses to CNG will aggravate global warming and diesel vehicles must be allowed to continue. So far the automobile companies have been trying to justify their move towards dieselisation by arguing that it is one of the solutions to the global warming problem. Now they are armed with support from consultancy groups to create confusion in the minds of the policy makers over the merit of the Supreme Court ruling on moving the entire bus fleet in Delhi to CNG. Their contention is that CNG will lead to higher methane emissions and cause global warming, thus diverting attention from the already very high lethal effects of severe particulate pollution in Delhi.

It is common knowledge that air quality regulators world-wide have to address the dual objectives of controlling air pollution and global warming. In the West, where global warming has emerged as a more serious and an immediate issue, the local pollution control authorities still give precedence to the problem of urban smog in pollution hot spots, primarily to protect health of local citizens. Policy action must be in accordance to the immediacy of the problem, and in the case of New Delhi, it is particulate pollution that poses immediate danger.

Methane is indeed a green house gas, though carbon dioxide is responsible for about half of the enhancement of the global green house effect. But in view of Delhi’s air quality profile, the benefits of moving to CNG outweighs the potential ills such as higher methane emissions. Delhi is reeling under particulate pollution load and according to WHO, particulate are responsible for maximum health damage and have no safe levels. Studies confirm that respirable particles kill even at low concentration and with minimal increase and their levels in Delhi reach as high as eight times the standards. Therefore, the priority in Delhi is to move out of fuels that emit more particles such as diesel as fast as possible. Let us get the facts right.

• Problem of toxic particulate emissions will be virtually eliminated.
• Total hydrocarbon emissions will be high but most of it is methane. The non-methane hydrocarbon components that are cancer causing and come mostly from diesel and petrol vehicles, constitute a small fraction of the total hydrocarbon emissions from CNG vehicles.

• The nitrogen oxide emissions though high compared to other emissions from CNG vehicles will still be much lower compared to diesel vehicles.
• Sulphur dioxide emissions that also leads to formation of deadly sulphate particles will be virtually eliminated.
• Carbon monoxide levels will be considerably lower.

It is shocking that while the immediate need is to phase in alternative fuel options, the New Delhi-based Tata Energy Research Institute (TERI), is insisting on prioritising the order of fuels by keeping diesel on the top. Aspiring for the "overall environmental balance", TERI has formed the "auto-oil-government- research forum" to facilitate collaborations among different agencies on fuel quality issues. But the forum cannot ignore the importance of prioritising target pollutants indefinitely.

Allowing polluting diesel buses to continue in Delhi will negate the very spirit of the Supreme Court order to promote CNG technology for an immediate impact on the air quality. Today, Delhi faces the challenge of lowering its particulate load by 90 per cent in order to make it safe to live. Any further increase in diesel vehicles will make this task impossible. Perhaps the most resounding answer to the global warming vs urban smog debate has come from the US. Faced with a similar dilemma the California environmental regulators made it clear that reducing emissions of greenhouse gases is not their priority; it is the responsibility of the us Environment Protection Agency (EPA) in Washington, dc. While reporting the debate in November 27, 1998 the New York Times quoted California Air Resources Board official stating that their "clear, unmistakable authority to enact regulations is to reduce urban smog. Global warming is an international issue and the us EPA ought to be the agency taking the lead."

Similarly, the Natural Resources Defense Council (NRDC), a New York based non-governmental organisation that runs the Dump Dirty Diesel Campaign across the us has not hesitated in campaigning successfully against phasing out of diesel and phasing in of CNG, even though the organisation works on the issue of global warming. Even the European countries that have earlier encouraged diesel to combat global warming are rethinking diesel. A study by the Swedish Environmental Protection Agency shows that while diesel cars use 20-25 per cent less fuel per kilometre, they emit 15 per cent more carbon dioxide per litre than petrol cars. As a result, the overall effect on carbon dioxide emissions is ‘negligible’.

We cannot allow slippage on CNG strategy, as this is only this fuel which is available today can help to drastically reduce particulates in Delhi. CSE feels strongly that the ultimate solution does not lie in promoting either petrol or diesel, but in promoting alternative fuel options and keeping the share of dirtier fuel low to meet our air quality objectives.