Acid rain accounted for more than 53 percent of Guangdong province's total rainfall in the first half of this year, a bulletin released by the provincial environmental protection administration on September 3 said.

The figure represents a 7 percent increase over the same period last year.

In addition, the area's rainfall's average pH level was 4.81, a 0.03-drop from a year ago.

Unpolluted rain has a slightly acidic pH level, about 5.2. The lower the pH level, the more acidic the rain.

A region with either an average pH level of 4.5, or one between 4.5 and 5.0 but with more than 50 percent of rainfalls qualifying as acidic, is considered to have a serious acid rain problem.

The delta cities of Guangzhou, Shenzhen, Zhuhai, Foshan, Dongguan, Zhongshan and Huizhou as well as Maoming and Zhaoqing in the west currently have serious acid rain.

Chen Guangrong, deputy director of the provincial environmental bureau, attributed the worsening acid rain to increasing nitrogen oxide emissions from vehicles and power plants.

"Sulfur dioxide has been reduced by 118,000 tons since 2006 through the province's desulphurization efforts," he told China Daily on Thursday.

"The increase of nitrogen oxide emissions is a greater contributor to acid rain creation.

"Guangdong has not yet begun denitration work, because many of the old power plants have not yet mapped out such plans," he said.

At a meeting earlier this year, Guangdong's vice-governor Lin Musheng said the province will develop a system to deal with composite air pollution in the Pearl River Delta region.

(China Daily September 8, 2008)