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Neighbors to blame for nation's acid rain: EPA

"In China, about 70 percent of its energy comes from fossil fuels. Pollutants can be carried long distances by air currents to Taiwan."

Lin Neng-huei, atmospheric sciences professor at National Central University

Airborne pollutants from neighboring countries such as China, Japan and Korea account for more than half of those creating acid rain in Taiwan, the Environmental Protection Administration (EPA) said yesterday.

A study by the EPA on acid rain suggests that several areas in northern Taiwan have been significantly affected by air pollution, recording on average a pH value lower than 5, which is the minimum safe value according to scientists. On the pH scale, the lower the number, the higher the acidity.

At two newly established air-quality monitoring stations on the top of Yangmingshan (陽明山) and on Pengjia Islet (彭佳嶼), Keelung, the probability of the appearance of acid rain is 90 percent, the EPA said.

Between January and July, the average acidity of rain at the two stations was 4.5pH, which is only slightly less acidic than that of vinegar.

According to scientists from National Central University and National Yunlin University of Science and Technology participating in the research, the situation could be attributed to airborne pollutants from other countries.

"Domestic pollutants don't affect the two remote air quality monitoring stations," Lin Neng-huei (林能暉), an atmospheric sciences professor at National Central University, said at a press conference held yesterday.

Lin said that about 85 percent of foreign airborne pollutants come from seven regions -- Japan, Korea, northeastern China, northwestern China, central China, southern China, the Indo-China Peninsula and the Philippines.

Acid rain is produced by the burning of fossil fuels. It is formed when emissions of sulfur dioxide and nitrogen oxides react in the atmosphere with water, oxygen and oxidants to form various acidic compounds, such as sulfuric acid and nitric acid.

"In China, about 70 percent of its energy comes from fossil fuels. Pollutants can be carried long distances by air currents to Taiwan," Lin said.

Statistics collected at 12 stations distributed around the nation show that the probabilities of the appearance of acid rain was 78 in the north, 50 percent in the east and less than 40 percent in the south.

Wu Sheng-jong (吳盛忠), deputy director general of the EPA's Bureau of Air Quality Protection and Noise Control, said that the EPA has been tackling air pollution caused by emissions from factories and automobiles for decades.

The total emissions of sulfur dioxide in Taiwan fell to 226,000 tonnes last year from 458,000 tonnes in 1991, Wu said.

In order to tackle acid rain, Wu said, Taiwan's data is shared with other countries through three international networks, including the US National Acidic Deposition Program, the Composition of Asian Deposition, and the Acid Deposition Monitoring in East Asia.

Lin said that acid rain accelerates the decay of paints and buildings and damages ecological systems.

According to Lin and EPA statistics, algae cannot survive in lakes with a pH level of less than 4.5 pH and fish will die if the pH level is less than 5.

"Acid rain is like a chronic disease that damages our environment gradually," Lin said.
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