“This pollution affects cloud formations, precipitation, storm intensity and other factors and eventually impacts climate. Most likely, pollution from Asia can have important consequences on the weather pattern here over North America,” Zhang said.
The study backs UN research that suggests a layer of air pollution, the “brown cloud,” regularly covers the upper atmosphere over Asia between January and March and could precipitate an environmental disaster that could affect billions of people.
Scientists say it is the result of forest fires, the burning of agricultural wastes, dramatic increases in the burning of fossil fuels in vehicles, industries and power stations, and emissions from millions of inefficient cookers burning wood and cow dung.
“The effects of the ‘Asian brown cloud’ have been linked to the retreat, over the last half a century, of glaciers in the Himalayas that supply water to major rivers, including the Yangtze, the Ganges and the Indus,” coauthor Harshal Pandve said.
Asian leaders have been slow to understand and act on air pollution, but are now aware of people’s anger. China, embarrassed by air pollution before the 2008 Olympics, says it is now costing its economy US$400 billion a year, or 6 percent of its GDP. Beijing last month pledged US$1.6 billion to reward cities for tackling it and said it planned to close 300 factories.
Meanwhile, Singapore has proposed a law which would allow it to fine foreign companies for causing cross-border air pollution.
Observers say passing new laws is not enough. In the Philippines, where car numbers are predicted to quadruple within 20 years, a brown cloud hangs over the mega-city Metro Manila most days, despite higher standards for vehicles and draconian laws.
“Most Asian governments are still concerned with economic development to the detriment of everything else,” Manila’s Clean Air partnership Vicky Segovia said. “We are not impressed by any of them.”
A world problem
Air pollution in 180 Indian cities is more than six times higher than WHO standards and is the country’s fifth-biggest killer. Improvements in car and fuel technology since 2000 have been nullified by the rise in car numbers and the poor quality of the fuel used.
African cities are increasingly choked in smog from the burning of poor-quality diesel engines and firewood. In Lagos, Nigeria, tens of thousands of inefficient generators and more than 2 million old cars are in use. The main teaching hospital says one in five of all admissions are now linked to respiratory diseases.
Air pollution causes about 200,000 early deaths a year across the US, with emissions from cars and trucks causing 53,000 and power generation 52,000, says Massachusetts Institute of Technology’s environment laboratory. California suffers most from air pollution (21,000 early deaths).
EU environment commissioner Janez Potocnik says poor air quality is the top environmental cause of premature deaths in the EU, causing more than 100,000 premature deaths a year and costing from ￡300 billion to ￡800 billion (US$495 billion to US$1.3 trillion) a year in extra health costs. Air pollution causes 29,000 early deaths a year in the UK and similar numbers in France and Germany. This month Paris curbed car use on one day to cut pollution.