For Asian skies and drivers, Michael Walsh has good news and bad when he talks about trends for the next 10 years. Walsh chairs the international Council on Clean Transportation, an independent non-profit providing research and technical and scientific analysis to environmental regulators. He also consults internationally on motor vehicle emissions and energy.

Walsh has been concentrating on China, and the situation there may apply elsewhere in Asia. If nothing is done, a decade from now China could see a doubling of emissions from the road fleet for NOx (nitrogen oxides) and other pollutants. Alternatively, the advent of low sulphur fuels and Euro 6 equivalent standards could change things dramatically.

“They could actually be reducing, slightly, their overall emissions in spite of what we think will be continued very high growth in the vehicle population,” Walsh said.

He’s cautiously optimistic that this improvement will come to pass. He noted that China has made significant air pollution progress since the 1990s. Further progress will require changes to both technology and the regulatory scheme. For instance, unlike the situation in other parts of the world, China’s Ministry of Environment doesn’t presently have the authority to regulate fuel quality, Walsh said.

Thus, it cannot mandate the appropriate parts-per-million levels of sulphur in fuel. This is important because control technology for cars and trucks depends on the availability of appropriately low sulphur fuel. Euro 6 technology, for instance, requires 10 parts per million (ppm) sulphur fuel.

China’s Ministry of Environment has proposed it be given the power to regulate fuel quality, Walsh said. In the meantime, cities such as Beijing have been negotiating with Sinopec and Petrochina directly so that they can implement China 5 and 6, the equivalent of Euro 5 and 6. Reportedly, these talks are about to bear fruit.

The situation in India roughly parallels that in China, with a split regulatory scheme. Thirteen of the largest cities have gone to a Euro 4 equivalent (Bharat IV), with a 50 ppm limit for sulphur in petrol and diesel fuel. The rest of the country is at Euro 3 level.

One of the problems with a two-tier emissions system is that vehicles travel. Consequently, they can easily fill up outside of one of the cleaner zones, while doing most of their traveling inside the area with tighter emission requirements. This sidestepping of pollution controls is a particular problem for certain vehicles.

“With trucks being usually a major source of both NOx and particulates, you lose a significant part of the benefit of your program if you don’t have a national program,” Walsh said.

Others also see the need for national action. Anumita Roychowdhury, executive director of the New Delhi-based Centre for Science and Environment, noted that growing diesel use in India is contributing to dangerously high levels of particulates. She added that Nox levels have also been increasing in Indian cities.

Studies by the Automotive Research Association of India have shown that emissions from uncontrolled diesel engines run as much as 10 times that of petrol engines, with NOx emissions five times greater and total air toxic emissions seven times higher, she said.

One problem looking forward is that the April 2010 introduction of Bharat III and IV, which are equivalent to Euro 3 and 4, is currently the end of the road. India has no announced plans for further emission control improvements. Additionally, Roychowdhury pointed to a growing price differential between petrol, which is highly taxed and freely sold, and diesel fuel, which is subsidized for agricultural use. One result is that diesel cars are increasing without clean diesel fuel, or a plan to get such fuel, in place.

Roychowdhury suggests the implementation of a national strategy, with investments in refineries so that they can produce 10 ppm sulphur fuel. There also should be funding sources created to clean up the air, and she also advocates the imposition of taxes and fees to correct the imbalance between petrol and diesel pricing.

“As equalization of the fuel prices is still way off, adopt an additional duty to target the end use of diesel in cars,” Roychowdhury urged.

This problem is not confined to India. Sophie Punte, executive director of the Clean Air Initiative for Asian Cities, noted that the increasing use of diesel across Asia is being driven, in part, by subsidies. These have the effect of pushing people to buy diesel cars. One fix is removing the subsidies. If that is not possible, then a different course of action may be needed.

“If subsidies are maintained for agricultural use only, as is the case in parts of China, then a good enforcement system is needed to prevent smuggling of subsidized diesel into the transport system,” Punte said.

Other options are to push for greater fuel efficiency, move toward a greater use of alternative fuels, and tighten emission regulations. Any of these could reduce air borne pollution and thereby improve the health of millions of people.

However, there is also another pan-Asian alternative: transporting people more efficiently without building more roads to handle more cars. This growing trend is the focus of a new initiative from the Manila-based Asian Development Bank (ADB), which funds projects that fight poverty in the region. Traditionally, its transportation funding has focused on roads. For instance, its funding for roads was 80 percent of its total transport projects in the decade ending in 2009. However, that figure will fall to about 40 percent by 2020. Over that same span, urban transport will soar from a few to 30 percent of the bank’s total transport funding.

Jamie Leather, principal transport specialist with the ADB, noted that this switch is being done in response to demands from countries. They are seeking to create a more sustainable transport system and at the same time deal with air pollution. They have to attack both problems in an increasingly urbanized society.

Solutions that meet these requirements involve the use of rail and other public transport methods. This could be a strong transport trend across Asia, in part as a way to improve the environment. Another reason is the limit on road building, Leather said.

“You cannot build your way out of congestion in urban areas,” he said.