Talking Point. Defogging Delhi’s air

Diesel has been a much-maligned automotive fuel for years now. And after the Volkswagen ‘Dieselgate’ emissions scandal, there has been renewed paranoia about the potential harm that diesel vehicular exhaust can cause. Entire cities, countries and governments have fallen foul of diesel.

However, the three-month ban on new car registrations by the Supreme Court on ‘so-called’ luxury diesel vehicles in the National Capital Region (NCR) is also likely to be ineffectual in finding a lasting solution to Delhi’s pollution problems.

It is gratifying to see that the court is now considering a blanket ban on all diesel cars, including the ones with smaller engines. But the slew of measures that the court and the Delhi government have come up with will continue to fall short of offering even a brief respite to the capital’s gasping lungs.

The issue needs to be broken down into parts to understand why these can’t be part of a model solution which can be emulated nationwide.

First, vehicular exhaust from engines of all fossil fuel types is harmful. Diesel engines tend to have a higher concentration of pollutants due to the presence of particulate matter (PM) and unburnt hydrocarbons.

Also, it is the concentration of one fuel type that increases the presence of specific pollutants. In the case of Delhi, all commercial vehicles are diesel-run and there has been increased popularity of diesel passenger cars during the last few years. This has led to a higher concentration of PM in the air.

According to the US Environmental Protection Agency, PM is a hazardous pollutant that is made up of organic chemicals, metals, acids of nitrates and sulphates, and soil or dust particles.

PM that is coarse and larger than 2.5 microns, but smaller than 10 microns, is unhealthy.

But the more dangerous and harmful PM type is the one that is smaller than 2.5 microns and invisible to the naked eye. This type of pollution is typically emitted by forest fires, power plants, heavy manufacturing industries and vehicles.

In the case of Delhi’s pollution, all of these are the contributors, except may be forest fires. But during winter, man-made fires are likely even bigger contributors.

Yes, diesel vehicle exhaust is the single largest source. But a blanket ban on all diesel passenger vehicles, before a viable alternative can be offered to the users, is not a sustainable solution. Also, there are other factors that need to be considered before maligning diesel cars.

If you look at the air quality data for Delhi collected by multiple sources, including the US Embassy and Consulates in India, the numbers are alarming.

The air quality index measuring PM 2.5 is considered hazardous and extremely unhealthy when it is in the range of 301-500. In many parts of Delhi (like Anand Vihar) it is often above 900, and in Chanakyapuri, where the US embassy is situated, it is often above 400.

There is an identifiable trend in the readings — all the areas of the capital where extensive construction work is going on and the ones with traffic bottlenecks have the highest levels of PM pollution.

Free flowing traffic can make a difference because the diesel engine’s exhaust emission is lower during the cruising cycle than in the initial acceleration cycle. So, ‘stop and go’ traffic will increase the amount of pollutants.

An improvement in traffic management will certainly help, as will better policing to ensure that the cars on the road are better maintained.

Ironically, Delhi still has among the best self-certification and monitoring infrastructure for checking if tail-pipe emissions are under control (PUC — pollution under control certificate). The fact therefore remains that Delhi has a ready-to-use monitoring and policing infrastructure.

One aspect that the court should not be swayed by is the rhetoric against the additional burden on the car buyer from the imposition of a green tax or the implementation of a more stringent emission standard such as Euro VI. In fact, a green tax must have been incrementally imposed on diesel cars even as the government started out on its mission to gradually narrow down the price differential between petrol and diesel fuels.

With the current low global oil prices, there couldn’t have been a more opportune moment to introduce a levy.

Diesel vehicles can’t be wished away as they come with inherent advantages, especially in urban driving conditions.

So, the way forward can involve disincentivising diesel car purchase but also has to simultaneously include improving public transportation infrastructure, better policing and traffic management, more stringent emission norms and delivering better fuel quality.

All other measures that involve moral suasion, like the odd-even number plate rule, can only provide temporary respite.