The acid rain situation nationwide has improved markedly in the past decade, dropping to an incidence rate of about 53 percent during that period, the Environmental Protection Agency (EPA) said yesterday as it announced the results of a 20-year monitoring project.
The EPA said that while acid rain was a rare occurrence in the 1970s, it gradually became more serious in the 1980s, especially in northern parts of the country, as well as near Tainan and Kaohsiung. Acid rain monitoring efforts began in 1990, using pH levels below 5 as a benchmark for acid rain, it said.
Hsieh Yein-Rui (謝燕儒), director-general of the Department of Air Quality Protection and Noise Control, said there are 12 acid rain monitoring stations scattered across the country, adding that data collected from 1999 through this year showed an average acidity level of pH 5.02.
Instances of acid rain remain more common in the north than in the south, it added.
Peng Chi-Ming (彭啟明), co-organizer of the research project and an assistant professor in atmospheric sciences at National Central University (NCU), said acid rain tended to occur more in the spring and fall when the northeast monsoon brings air that is laden with particulates.
The area surrounding Jhongli (中壢), Taoyuan County, has the worst acid rain problem in the nation, with an incidence rate of 75 percent.
About 100 percent of the rain that fell in that area during winter was acid rain, Peng said.
The two principal causes of acid rain in Taiwan are polluted air from abroad — mainly China — and local pollution, said Lin Neng-huei (林能暉), co-organizer of the project and professor of atmospheric sciences at NCU, adding that the two were equally responsible.
However, fog can be more acidic than rain because it contains less water and a higher density of acidic substances, Peng said.
A lot of people fear that being exposed to acid rain will cause baldness, Peng said.
“Actually, getting rained on by acid rain is more of a long-term problem ... if you are exposed to it every day, then eventually it can cause some harm,” Peng said.
Hsieh said the EPA would continue to enforce regulations to control air pollution, as well as communicate with China on the technical aspects of controlling the problem.