Asia's air pollution 'circles the world for years': report

WASHINGTON — Pollution from Asia's booming economies rises into the stratosphere during the monsoon season then circles the world for years, according to a report out Thursday.

A study by the Boulder, Colorado-based National Center for Atmospheric Research (NCAR) said the strong air circulation patterns linked to Asia's monsoon rainy season serves as a pathway for black carbon, sulfur dioxide, nitrogen oxides and other pollutants to rise into the stratosphere.

The stratosphere is the layer of the atmosphere located some 32 to 40 kilometers (20 to 25 miles) above the Earth's surface.

"The monsoon is one of the most powerful atmospheric circulation systems on the planet, and it happens to form right over a heavily polluted region," said NCAR scientist William Randel, the study's lead author.

"As a result, the monsoon provides a pathway for transporting pollutants up to the stratosphere."

Using satellite data and computer models, the scientists found that once the pollutants are in the stratosphere they circulate around the globe for several years.

"Some eventually descend back into the lower atmosphere, while others break apart," read a statement on the study.

Researchers fear that the impact of Asian pollutants on the stratosphere may increase in the next decades due to fierce industrial growth in countries like China and India.

Scientists however do not know the impact of climate change on the Asian monsoon, unsure if it will strengthen or weaken the monsoon's vertical air movements.

The international study, published in the March 26 edition of the journal Science, was funded by the National Science Foundation together with the National Aeronautics and Space Administration and the Canadian Space Agency.