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Air Pollution in Delhi Increasing with Rapid Growth in Diesel Cars

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.


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.



Looks like they are way behind the USA, diesel fuel limits for sulfur should be less than 15 ppm, not 350 ppm. The vehicle limits should be close to tier 2, bin 5 limits.


Headlines like those on this article are the reason Bjorn Lomborg's book did so well. Please - call a spade a spade!

Pollution clearly has little correlation with the number of vehicle registrations in Delhi - otherwise it would have increased rather than decreased across the 8.5 year span of the data. This does not mean that the increased number of cars has no effect on pollution - simply that the contribution of all those new cars is not significant compared to other factors which changed over the 8.5 years.

When misuse of data like this is discovered by the general public it creates skepticism of both scientists and the environmental movement. If people in the media and scientists seeking funding pull this kind of stunt enough, people might start to doubt they're telling the truth about things like global warming. But then I guess its too late to close that barn door.


Cue anti-diesel wingnuts...NOW!


I'm starting to think the best solution for humanity is all out nuclear war... NOW!

We'd save the oceans -- stop global warming... we'd just zap out the city / high population areas & return to a decent, livable number of humans on the planet.

We'd also maybe become more thoughtful & peaceful.

Crazy thought? I'm not so sure.



Matt, let's start with you. Then that would make one less human to worry about.


Cue anti-diesel wingnuts...NOW!

Cue OCD... now.


Looks like pretty small gains to me considering the enormous increase in cars. "Over the last ten years diesels have increased 425%."



Looks like pretty small gains to me considering the enormous increase in cars. "Over the last ten years diesels have increased 425%."

That's certainly an outlook one could adopt if one didn't read that in context.


Until I see speciation of the PM there, count me also skeptical of the conclusion reached in this report that light-duty diesel vehicles are the primary cause of the apparent increase in ambient PM concentrations.


Sounds like they already have a handle on what they should be doing. More stringent emissions standards would be one obvious tool to combat this. This article belongs in the category of "yeah, that's about what I would expect."


If you were living in Paris, or any other large European city, you would understand what "nullifying the impact of clean air programmes" means. Especially if you were asthmatic. Diesel is NOT ready for your lungs. Even the "clean" ones we are supposed to have here.

Roger Pham

That's why HEV's are so valuable to maintain clean air standard. But, the ultimate will be H2-vehicles and BEV's and PHEV's, providing that the smoketacks for the coal-fired power plants will be kept at sufficient distance from the city limit.


I don't think the people of Delhi can afford HEVs.
Their GDP / head is $660 for 2005.
The GDP at PPP is $3400 but you have to buy Prii from Japan at world exchange rates.

I guess the best thing they could do is to try to get people into CNG cars ( as they did with buses some time ago) but you lose boot space and power.

Or clean up the diesel. Who can blame them from wanting the most efficient cars.

I think we will be seeing a lot of this in 3rd world cities - so it is a worthwhile problem to solve - what is the cheapest way to clean up a diesel ( or produce a hybrid ).

Roger Pham

The cost of a HEV is but 10-20% over that of a regular model. So, a 660cc mini-mouse car if made into a HEV using a tiny battery pack and a tiny electric motor with an equally small power electronic control would not cost a whole lot, probably 1/2 to 1/3 the cost of a Prius. The price of computer chips is going way down.
A shorter range CNG car would not take up too much boot space, as the CNG tank can be the same size as the gasoline tank, if one is content with a shorter range...or not...if one uses a CNG-HEV car!


In the "fuehrende" econemy in Europe the Diesel-cars average output of CO2 has passed the average output of patrol-cars! 174 to 172 g/km.

Nothing to celebrate of course.

As in Dehli the Diesel is a counter productiv step in improving air quality. In Europe the Diesel-engine has had only one aim: to give the European car manufacturer an advantage against the Asien car manufacturer (and the Fench and Polish farmers). Europeans like Peugeot and VW could focus on Diesel whereas the Japanese had to develop patrol-engine as well (for the home market and the US).

With the Diesel, we have got the SUV boom in Europe. It´s a shame!

Only recently the Europeans have recognized their fault. VW has developed the TSI. The Frenchies are improving their patrol engiens as well. Unfortunately, the Diesel is already established one the market; as high NOx/Ozon and PM emissions are common in Paris, London and Rom.

Any you guys, ralling for the Diesel, you should move to Paris an enjoy the air quality: The air quality is great, thanks to small high efficent 4 cylinder turbo charged Diesel engiens! How would it be with high efficent Prius car that cost around the same the avergage European consumer is spending for his car? Or with cheap Toyota Aygo and derivates?

Harvey D.

Diesels are NOT clean engines. Check the distance between the school and highway used heavily by diesel engine vehicles before you send your children there. Anything closer than 3 miles is too close.

PM produced by Diesel engines will damage your lungs as much as smoking and/or asbestos, if you're exposed more than 8 hours a day.

This problem is well known in Europe but most Europeans avoid talking about it because Diesel fuel is much cheaper than gasoline (less taxes) and money talks. Secondly, in some cases, they get better mpg. However, gasoline Japanese Hybrids get equivalent or better mpg with a lot less harmful pollution.

Wood stoves/fire places are just as bad and also tolerated in Canada and northern (USA) States. Respiratory disorders (especially in children) can go up as much as 300% in areas where this type of combustion is used often. Knowing that, we still use a many million such pollution devices and would be willing to drive diesel vehicles to save a few pennies.

We have become very smart....

fyi CO2

Appreciate your minority insight on diesel in Europe, Michel. You are being sarcastic about great air quality in Paris, certainment?


Talking about diesel emissions has always seemed odd in the states because business has an interest in keeping costs down, so that's something of a confound from what I've gathered. Low sulfur fuel was only introduced here recently, and the potential of a decent diesel emissions system via Honda is within a couple years of a significant drop in allowed heavy diesel emissions by the EPA. Coincidence? Probably. But it's financially prudent for companies to keep costs down, so as long as it's cheaper to sucessfully fight something rather than accepting the costs associated with it, it will be fought. Like prop. 87 in CA, iirc there was something like ~$100 million spent by special interests (guess who) to fight it, but the bill could've resulted in $20 billion in taxes. Definitely worthwhile to fight. I figure diesel emissions systems follow the same trend.


good god!!!!! you people are sooo boring!!!! you have absolutely nothing to do!!


hello sir,i am ankur jain i am shift in m.p. i want your dealer ship in bhopal

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