THE air blowing from East Asia is about 10 times dirtier than that over the Pacific Ocean and poses a long-term threat in terms of climate change, a NASA mission has found.
The United States space agency is in Hong Kong this week to conduct tests for a global study on climate change and is working with the Royal Observatory and the Hong Kong Polytechnic.
Dr Robert McNeal, who is managing the study for NASA, said pollution levels soared as their specially equipped DC-8 plane approached Hong Kong from Guam.
They hit a cold front blowing from China that contained levels of nitrogen oxides 12 times higher than over the Pacific, and carbon monoxide levels nine times higher, he said.
These pollutants interfere with the atmosphere's ability to rid itself of greenhouse gases, which can lead to global warming.
An earlier NASA visit, in 1991, found 20 per cent of nitrogen oxides over the Pacific were from industrial activity - despite being thousands of kilometres from any human settlement - and the level is feared to be rising.
Dr McNeal said: ''We're seeing clear evidence of long-term, persistent pollution loads and we expect that to increase as human activity increases.'' The region's phenomenal economic and population growth rates were a problem in this respect, he said.