Sulfur dioxide is the main cause of acid rain  A region is plagued by acid rain  In order to improve this situation, the region has reduced 118000 tons of sulfur dioxide from January to June, a year-on-year decrease of 9 1%  According to the monitoring, although the content of sulfur dioxide in the air in this region has decreased, the frequency of acid rain has increased by 7
1%
Part of the sulfur dioxide in the air in this area drifts from the surrounding areas