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Cleaning up air pollution in developing countries
SURVEY: DEVELOPMENT AND THE ENVIRONMENT
Yellow skies, smarting eyes
Mar 19th 1998
From The Economist print edition
Clearing the air can be politically tricky, but need not cost a lot
ON COLD days in Delhi, the poor light bonfires of tyres, trees and rags whose fumes mix with the exhaust from the city's 2m vehicles to form a thick smog. On most days in Mexico city, a blanket of pollution cuts off views of the surrounding mountains. On one famous occasion it got so bad that birds fell dead out of the sky on to the Zocalo, the city's main square. Throughout the developing world, smogs in many big cities are getting worse as more people use cars and more manufacturing firms are belching out pollution. Congestion is on the rise too: according to one estimate, a car in Bangkok now spends the equivalent of 40 days a year stuck in traffic. The air in Asia's cities, like the water in its rivers, is particularly unhealthy, containing levels of dust and smoke several times higher than in the rich countries� cities.
Environmentalists in the developed world also worry about air pollution in poorer countries, not just out of the goodness of their hearts but because they fear it may affect their own backyard. Carbon-dioxide emissions, thought to be the cause of global warming, are growing particularly fast in developing countries. So are emissions of sulphur dioxide, blamed for acid rain which sometimes falls hundreds of miles from the source of the pollution.
But the harm that air pollution causes in the developing countries themselves is much more serious and immediate. The biggest causes for concern are indoor air pollution, lead emissions and small particles. Indoor air pollution in poor countries is not much talked about, but it is often as damaging to health as smoking cigarettes. Around a third of all energy consumed in developing countries comes from wood, crop residues and dung, which are often burnt in poorly designed stoves within ill-ventilated huts. Studies of women in India and Nepal exposed to smoke from such fuels show that their death rates from chronic respiratory disease are similar to those of heavy smokers.
Lead has long been known to be dangerous in large doses: some historians have argued that its use in piping and amphorae in ancient Rome caused many emperors to go mad, accelerating the collapse of the Roman empire. But only since the 1970s have scientists been aware that relatively small quantities of lead in the bloodstream can be harmful to humans. In particular, many studies show a correlation between levels of lead in children's blood and lower IQ scores, hearing loss and hyperactivity. In cities in developing countries, people take in lead mostly by breathing in air polluted by burning leaded petrol.
But the kind of air pollution thought to cause the most damage to human health in developing countries is that from small particles (of less than 10 microns in diameter, known as PM10). Caused by vehicle exhausts, coal-burning, smoke from factories and dust stirred up by vehicles, these particles easily find their way into people's lungs. Although doctors disagree about the precise mechanism by which they cause illnesses, studies the world over have shown a strong positive correlation between levels of PM10 in the air and death rates.
Together, these pollutants impose a big toll. The World Bank estimates that in China, which probably has the dirtiest air in Asia, air pollution in 1995 caused 178,000 premature deaths among city-dwellers and 1.7m cases of chronic bronchitis. The bank put the total economic costs of this damage at $32 billion, or almost 5% of the country's GDP. Similarly, preliminary estimates of the cost of last year's smog across South-East Asia suggest that for some of the countries affected it may exceed 2% of GDP.
Indoor air pollution is inextricably linked with poverty, and should therefore become less of a problem as living standards rise and families can afford to switch from dung and wood to cleaner fuels such as kerosene, liquid petroleum gas and, cleanest of all, electricity. Energy in developing countries, like water, is often heavily subsidised; in the early 1990s, the average price paid for electricity by consumers in these countries was 4 cents per kilowatt hour, when it cost an average of about 10 cents to produce. The usual argument for such subsidies is that they make electricity affordable for poorer people and thus improve their lives; but first those new consumers need to be connected to the grid, and in developing countries that privilege is largely reserved for the urban middle classes, who live in places where such luxuries are available.
In practice, therefore, subsidies are not as helpful to the poor as is claimed. At the same time they put a heavy burden on public spending, and they encourage the profligate use of power. So reducing subsidies and raising prices, although politically difficult, is a cheap and effective way of preventing waste. In recent years many developing countries have been moving in that direction. In Russia and Eastern Europe, manufacturing firms once kept going by subsidised energy have been allowed to collapse; and in China, energy intensity (the energy consumed per unit of GDP) has dropped by 50% since 1980. Even so, energy subsidies in developing countries remain high.
Another cheap and effective�and politically less contentious�anti-pollution policy is for governments to phase out lead in petrol, or at least encourage drivers to use unleaded fuel by taxing it less heavily. Typically it costs between 1 or 2 cents per litre of petrol to modify refineries to produce the unleaded sort, and although some drivers fret that unleaded fuel might damage their car engines, the effect is negligible. In recent years many developing countries, including Mexico and Thailand, have copied rich countries in reducing or phasing out lead in petrol; but others have not. In Africa and the Middle East, fuel with a very high lead content is still widely used.
In big Asian cities, motorcycles and three-wheelers account for much of the growth in vehicles because they are cheaper than cars; but they emit huge amounts of small particles and smoke. A cheap solution would be for governments to make four-stroke engines on these bikes compulsory, or at least encourage their use through differential taxation. Four-stroke engines are cleaner, and although they cost more to buy (putting off many would-be users), they cost no more in the long run because they are cheaper to maintain and need less fuel. Thailand, persuaded by these arguments, is phasing out vehicles with two-stroke engines.
Driven mad
Governments in developing countries have found it relatively easy to lean on big polluters such as factories and power stations, but much harder to persuade small polluters to change their behaviour. In Mexico city, for example, lead levels in the air have fallen by 98% since 1988, largely because Pemex, Mexico's state-run oil monopoly, introduced cleaner fuels. But levels of ozone and small particles in the air remain dangerously high. During 1996, for example, there were only 39 days when ozone in the city's air was "satisfactory" by World Health Organisation standards. In 1989, when popular anxiety about air pollution was at a peak, the city government introduced a scheme known as hoy no circula, which banned certain classes of car from use on certain days of the week. It also required drivers to get their cars checked twice a year, and to get them fixed if they failed an emissions test.
These measures produced some embarrassing results. Many families bought a second car�often a cheaper and more polluting one�so that they could drive on the days when their first car was off the road. The total number of journeys made by each family went up. A recent World Bank study concluded that in the longer run the hoy no circula programme actually added to air pollution. The inspection of cars, meanwhile, was undermined by corruption: many private garages offered to get cars through the emissions test in exchange for a bribe.
Now both schemes have been revised and improved. Inspections of cars, for example, are now carried out in fewer, more tightly controlled centres, and everything is videotaped by government regulators. But there are plenty of other places where regulations are widely ignored. China, for example, does not bother too much about enforcing its extremely lax emission standards, which permit some 40 times more carbon monoxide and eight times more nitrogen oxides than American standards. In Bangkok, regulations to reduce the amount of dust billowing from the city's numerous construction sites are widely flouted.
The obvious way to avoid the pollution problems so common in cities in developing countries is to plan their growth more carefully, so that people have less need to move around by car or motorbike. Most of these cities have grown haphazardly, with migrants from the countryside building illegal settlements (see article). Many of the biggest cities in developing countries, including Sao Paulo, Mexico city and Jakarta, have sprawled outward, rather like cities in North America. A better model might be the denser cities of Europe where people need to travel shorter distances and rely less on cars. Investment in public transport can help, although governments in developing countries are often tempted to spend on hugely expensive systems�such as underground railways�when buses running on exclusive bus lanes would do the same job much more cheaply.
The Brazilian city of Curitiba seems to have cracked some of the problems of urban planning. Its population has grown from only 300,000 in 1950 to over 2m today, but the local government managed the flood of migrants by channelling urban growth along five corridors stretching away from the city. Each corridor is served by a road with exclusive lanes for high-speed buses. Although Curitiba is relatively wealthy, with high rates of car ownership, it has cleaner air and lower petrol consumption than most comparable Brazilian cities.
Urban planners continue to debate whether it is environmentally friendlier to concentrate a city in a single, densely populated urban area or to develop a number of smaller, densely populated "nodes" separated by green space and linked by fast transport. Whatever they do, some sort of plan for a city's growth is better than no plan at all. In many cities in developing countries, maps of urban areas are decades old, the planning process is governed by kick-backs, and the various departments responsible for transport, zoning laws and environmental protection barely talk to each other. No wonder such a mess on the ground makes a mess in the air.
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Source: The Economist
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