Airborne pollutants

Aerosols from Asia are poisoning the environs of the Pacific Ocean, say researchers

Published: Saturday 30 September 2000

EACH year, millions of tonnes of toxic aerosols from Asia travel across to the Pacific Ocean, according to a study conducted by researchers at the University of California at Davis (UCD), usa. According to them, these previously undetected toxic pollutants, which are a result of increased industrialisation in the region, travel with the wind currents. The findings are a result of analysing data for the past 11 years, says Thomas A Cahill, a UCD professor who headed the research.

These pollutants are responsible for diseases and the destruction of crops in Asia, says researchers. They might now be moving towards USA, polluting water and causing dramatic change in global climate. "Aerosols from Africa sometimes used to hit the East Coast of America. There were evidences that aerosols from east Asia reached up to Hawaii. It is not surprising if they have reached the West Coast as well," says A P Mitra, a scientist at the National Physical Laboratory (NPL) in New Delhi.

According to Cahill, dust storms that used to occur every spring in Asia sending soil across the Pacific, now there is evidence that same amounts of sulphates and organic aerosols are also transported towards the US.

"Although these aerosols are not of immediate threat to the US, they can have a disastrous effect on Asia. Around 20 per cent of agriculture is "depressed" over much of China due to aerosols," says Cahill.

The information on the aerosols originating from Asia is considered to be of vital importance because of three reasons. First, the Northern Pacific Ocean is one of the few clean areas of the Northern Hemisphere. Polluting it would mean disturbing the balance of heating and cooling of the ocean which in turn will affect weather conditions. Second, evidences of "toxic Asian pollutants" are increasing in the waterbodies of North America.

But the most important and direct correlation is the link between aerosol levels and rates of illnesses and deaths of people. Asia, Cahill says, is the largest source of aerosols in the world. They originate from the millions of tonnes of coal burnt in power plants, locomotives and from heavy industries and automobile emissions.

According to Mitra, the aerosols can definitely bring about changes in regional climate. "The aerosols have heating and cooling effects depending upon what they consist of. These effects can bring about changes in the climate of a region. Since aerosols can be transported to other regions of the world, they can change climate in those regions as well," he says.

When the aerosols are released into the atmosphere, they move with the winds at high altitudes where the winds are drier and faster. They carry the unique characteristics of their land of origin with them and in the form of trace elements such as copper, nickel and zinc.

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