The research was jointly conducted by the Tibetan Institute of Plateau Atmosphere Environment and the Belgern University of Norway.

According to research results, a drop in ozone density on the plateau is quicker than in other parts of the country.

The ozone content there goes down markedly in the summer every year. But there was a slight variation in the amount of ozone in the past four years.

The observation in other parts of China shows that ozone had decreased in Heilongjiang, Zhejiang and Qinghai provinces and the cities of Beijing and Kunming.

China has devoted much attention to ozone protection since the country established ties with the World Meteorological Organization's ozone monitoring network in 1978.

Altogether five monitoring stations have been launched in the country. As a measure to protect ozone, China has decided to phase out ozone-depleting substances as cleaning agents before 2010.

(Dragon news net)