The "atmospheric brown clouds" (ABC) result from the burning of fossil fuels and biomass, and in some areas also amplify the impact of climate change brought on by greenhouse gas emissions, the U.N. Environment Program (UNEP) report said.
The ABC also make the skies in at least 13 major Asian cities up to 25 percent dimmer and contribute to public health hazards, the report says.
The 10,000-foot-thick (3-km) layer of soot and industrial pollution has been observed stretching from the Arabian Peninsula to China and the islands of the western Pacific.
Some researchers involved in the study said they were concerned the dimmer sunlight could threaten agricultural production for 3 billion people in the region.
The ABC also appear responsible for accelerated melting of some Asian glaciers.
“One of the most serious problems highlighted in the report is the documented retreat of the Hindu Kush-Himalayan-Tibetan glaciers, which provide the headwaters for most Asian rivers, and thus have serious implications for the water and food security of Asia,” said lead scientist Veerabhadran Ramanathan of the US-based Scripps Institution of Oceanography.
Initial findings released in 2002 about the existence and impact of the brown clouds were met with skepticism. But more extensive research has brought about a consensus that they do exist and pose a threat to humankind.
“I expect the atmospheric brown cloud (ABC) to be now firmly on the international community's radar as a result of today's report,” UNEP Executive Director Achim Steiner said in a statement.