"This study has shown that the level of atmospheric pollution across most of the country is two to five times larger than what the World Health Organization guidelines call for and it's home to one-sixth of the world's population," Di Girolamo said.
The MISR data show very high levels of both natural and manmade aerosol pollutants in the air over the Indian subcontinent, but the longitudinal study also revealed some surprising trends. For example, the researchers noticed consistent seasonal shifts in manmade versus natural aerosols. The winds over the subcontinent shift before the monsoon season, blowing inland instead of out to sea. The air quality during the pre-monsoon season is notoriously bad as these winds carry an immense amount of dust from Africa and the Arabian Peninsula to India.
"Just before the rains come the air gets really polluted, and for a long time everyone blamed the dust," Di Girolamo said, "but MISR has shown that not only is there an influx of dust, there's also a massive buildup of manmade pollutants that's hidden within the dust."
During the monsoon season, rains wash some of the dust and soot from the air, but other manmade pollutants continue to build up.
During the post-monsoon season, dust transport is reduced but manmade pollutant levels skyrocket as biomass burning and the use of diesel-fueled transportation soar. During the winter, seaward breezes disperse both natural and human-generated pollution across the subcontinent and far out to sea until the pre-monsoon winds blow again.
The MISR data also revealed an especially dense area of manmade particles in India's Gangetic Basin, in the foothills of the Himalayan Mountains. This raises questions about the effects that soot and other particles may be having on weather patterns and water sour
|Contact: Liz Ahlberg|
University of Illinois at Urbana-Champaign