The detractors are trying to project the rising NO₂ levels as a mere local problem in Delhi and blaming it only on CNG vehicles, glossing over the fact that NOx is fast emerging as a national problem. This will require immediate scrutiny and action. Why do cities such as Pune, Kolkata, Faridabad and Bangalore that do not have CNG, also have rising NO₂ levels?

The Centre for Science and Environment (CSE) is shocked to note that even as the air quality data of the Central Pollution Control Board (CPCB) shows increasing nitrogen dioxide levels in several Indian cities, no official explanation is available. Instead, only Delhi is singled out, and the CNG programme is blamed for the rising NOx levels. Even other cities such as Faridabad, Kolkata, Pune, Bangalore that do not have a CNG programme, also show rising NOx levels (See graph).

Our air quality regulators refuse to acknowledge the looming air pollution challenge. While particulate levels are still high, NOx has begun to rise, too. But there is still no policy recognition of the dire consequences of the city getting caught in the crippling grip of NOx and particulates. This blatant disregard puts at risk the efforts that are being made in cities like Delhi to control alarmingly high levels of air pollution. With all the recent measures, including the largest-ever CNG programme, Delhi has just about succeeded in stabilising particulate pollution. The just-released study by the World Bank and the Clean Air Initiative for Asian cities shows that Delhi had the highest average particulate levels during 1990-1999, and still ranks as the most polluted in Asia -- even after lowering the levels substantially during 2000 – 2003.

This exposes the challenge of implementing much harder decisions to further lower particulates. But the government has not even explored solutions to lower NOx.

CSE’s rapid assessment of CPCB’s air quality data for Delhi and some other Indian cities bear out the following NO₂ trends that are still ignored by air quality regulators:

• CPCB data exposes that in several Indian cities, such as Pune, Faridabad, Bangalore, and Kolkata, NO₂ levels are rising consistently over the past few years. What is contributing to the rising trend in these cities that still do not have a CNG programme?

• Close scrutiny of Delhi’s air quality data shows that the average annual NO₂ levels have begun to exceed the standards only in two heavy traffic sites -- ITO and Town Hall. During 1997 and 2001, the levels at ITO have hovered between 59 microgramme per cum to 67 microgramme per cum, as against the annual average standard of 60 microgramme per cum. In 2003, the annual average levels have exceeded standards by 1.6 times. The monthly average levels reported so far for 2004 show a decline as compared to the previous year.

• Though the NO₂ levels in other sites in Delhi are still lower than the permissible limit, it is possible to detect a steady rise over time, which requires urgent attention. In all other sites in Delhi, the lowest average level reported during 1997 - 2002, was 19.4 microgramme per cum, while the highest average reported was around 39 microgramme per cum – both far below the annual average standard of 60 microgramme per cum.

While officials are silent on the possible contributory factors, a cursory review shows that the NOx rise in Delhi coincides with a higher penetration of new diesel cars, much deeper penetration of four-stroke two-wheelers, and the implementation of the CNG programme.

• The phenomenal spurt in diesel car sales – 106 per cent annual incremental increase since 1999 -- leads to higher NOx levels. These are legally allowed to emit three times more NOx than petrol vehicles. Leapfrog to Euro IV standards to reduce diesel’s unfair advantage or restrict diesel car sales.

• Emissions from a poorly maintained CNG fleet can increase NOx. This would require measurement of NOx emissions from the CNG fleet under the vehicle inspection programme. But such measurements are not possible under the current PUC system. Accurate NOx measurements will require more advanced testing facilities. Immediately begin to monitor NOx emissions from the in-use CNG fleet. There is no reason why CNG vehicles cannot maintain their low emitting characteristics with disciplined, preventive maintenance.

• Four stroke engines that comprise nearly 80 per cent of the new two-wheeler sales in the city also emit several times more NOx than two-stroke engines. Enforce stricter norms for NOx emissions for two-wheelers.

• Power plants in Delhi can also contribute high NOx. Closely monitor and enforce stringent NOx standards.

NOx may prove extremely difficult to control in the future. Unlike other air pollutants, nitrogen oxides have a more complex life cycle. NOx triggers the formation of more harmful pollutants, such as ozone. Surprisingly, ozone has not as yet been assessed adequately in Delhi or in any other city in India.

Instead of being so eloquent with superficial judgments on local air quality, the Ministry of Environment and Forests needs to spruce up their monitoring capacity to be able to track changes and act on them. All new technology solutions to particulate, carbon monoxide and hydrocarbon emissions are today traded for higher NOx emissions, because engineering solutions to reduce one only increases the other. A more holistic approach is called for - stringent technology standards together with effective controls on the rising numbers of vehicles.

CSE demands an immediate assessment of the impact of these developments on NOx levels, and a strategy to control NOx designed not only for Delhi but for other Indian cities as well.

Raising alarm is easier than finding solutions. Achieving the very low levels of NOx, PM and toxins from all categories of vehicles presents a very serious challenge to air quality regulators and the vehicle industry. Acknowledge it and act on it. Don’t just look for easy scapegoats.