2. Current Pollution Problem.
Friday, June 11, 1999 Published at 17:20 GMT 18:20 UK BBC
Pollution cloud threatens Asia.
A thick brown cloud of pollution the size of the United States has formed over the Indian Ocean, contributing to acid rain and cutting the amount of sunlight reaching the water.
The cloud, a mixture of pollutants from vehicle and industrial emissions, and could wreak havoc on the region's climate and marine life. Scientists sponsored by the US National Science Foundation spent six weeks earlier this year tracking the cloud with aircraft, ships, balloons, and satellites.
The cloud contains soot,chemicals and carbon monoxide.
The INDOEX project has mapped the extent of the cloud. The INDOEX project has mapped the extent over the Indian Ocean .
INDOEX, revealed that the affected area includes most of Asia and the northern Indian Ocean, the Arabian Sea, and much of the Bay of Bengal - nearly 10m square km in total.
The cloud consists of tiny particles of soot, chemicals and carbon monoxide by-products of burning fossil fuels.
During the winter monsoons, the cloud blows out from Asia over ocean, and during the summer wet season it reverses direction to back over the land.
Levels of sunlight are drastically reduced, and threatens Asia
Scientists from the Scripps Institution of Oceanography in San Diego, which coordinated the project, say the pollution is unprecedented in the region's history, and will get worse as the population increases.
Aerosol use, which has long been known to promote global warming, is still widespread in Asia. This is very serious situation. The tiny particles in the cloud reflect the sun's rays, cutting its heat by up to 10%. In the ocean, less sunlight could threaten the survival of water-plants and plankton - key organisms in the world's food chain. Reduced sunlight also means that less water evaporates from the ocean - leading to lower rainfall and increasing the risk of drought.
Scientists now want to discover how permanent the cloud is, and whether it is growing.