In a twilight zone

  • 30/01/2002

In a twilight zone Unmasking the dragon
Two and three wheeler population is exploding in Asia. The health implications are scary: they emit dangerous pollutants that have gone unnoticed till now

ASIANS are riding high on dragons that they cannot get off. The dragons are small but far too many. Consider this: About 85 per cent of traffic on Hanoi's streets consist of bikes. In Taiwan, one only needs to divide the country's population by two to get the number of motorcycles. About 70 per cent of the vehicular fleet in India consists of two and three wheelers. China produces almost thrice the number of vehicles as India. It's a situation that is unique only to Asia in more ways than one. More than 90 per cent of the world's two and three-wheelers are produced in Asia and the region boasts of some of the most polluted cities in the world. Perturbed by such trends, emission watchers warn, "Get ready for a public health catastrophe."

The warning is apt. Pollution load from this segment of automobiles is enormous and scientists are finding new evidence about pollutants from these vehicles. "Two and three-wheelers constitute three-fourth of the Asian vehicular fleet. These emit up to 70 per cent of the total hydrocarbons, 40 per cent of the total carbon monoxide and a substantial part of the particulate pollution in the region," says Jitendra Shah, an environment engineer at the World Bank who has done extensive research on these vehicles.

The fact that these vehicles emit particulates is new. But frightening in terms of public health. The problem is particularly difficult in the case of two-stroke technology, which makes up the majority of the fleet on road. Two-strokes have a problem because of their inefficient combustion which leads to deadly emissions in the form of unburnt hydrocarbons. An estimate by Michael P Walsh, a US-based international expert on vehicle technology, shows that at some traffic intersections in Bangkok, motorcycles contribute more than 47 per cent of the total particulate load. Till now, there was little information about the particulate emissions - tiny pollutants which are inhaled deep into the lungs - and as a result nowhere in the world are particulates from two-wheelers even regulated.

For Delhi, the situation appears grim. If public transport shifts to compressed natural gas (CNG), two-wheelers will become the biggest polluters, estimates the Centre for Science and Environment (CSE), a Delhi-based non-governmental organisation (NGO). Futhermore, people using three-wheelers are the most vulnerable to exposure to particulate pollution in Delhi as compared to others who drive cars and other vehicles, estimates Sameer Akbar, a pollution specialist with the World Bank. For India's small towns that are teeming with diesel-fuelled three-wheelers, the situation could be potentially lethal.

But still little is known. The single study on two-stroke three-wheelers from Bangladesh by the Automotive Research Association of India (ARAI) had a shocking estimate: they emit nearly seven times more than the standards prescribed for trucks in India. Now new studies are confirming Asia's worst fear: two and three wheelers are deadly sources of particulate pollution. But still actual studies are few. The US, which does not have a concern for two-wheelers has done some of this work. For example, a study on snowmobiles has thrown up the danger of particulates (see box: Running on thin ice).

But the picture is far from complete. Another unnoticed pollutant benzene, a confirmed carcinogen, is a strong suspect. In most Asian countries, neither the benzene content in petrol nor the total aromatic content is controlled. The problem is compounded by the fact that two-wheelers do not have catalytic converters and other after-treatment devices, which would have been able to reduce benzene emissions. This, combined with the two-stroke technology with its unburnt hydrocarbons emissions, makes scientists believe that benzene emissions from these vehicles could be deadly . But as yet, typical of Asia and its scientists, there are few studies to estimate this public health impact of two-wheelers. The problem stares us in our face. But our scientists can rarely see beyond their noses.

A recent workshop discussing the emissions from two and three-wheelers reasserted that regulations to control particulate emissions were not on any country's agenda. Walsh, participating in the workshop organised by the Asian Development Bank, Vietnam Register and the United States-Asia Environment Partnership at Hanoi, said, "Though we know that particles are hazardous, there is very little chemical analysis of particles from two-stroke engines." This is the challenge. "Asia will have to take the lead in conducting studies and formulating regulations to reverse the growing air pollution threat. Industry must use the precautionary principle to invest in cleaner technologies," adds Walsh.

Related Content