Acid rain is caused when coal or oil is burned, which in turn generate vast amounts of polluting gases. Airborne by-products of certain industrial processes add to the pollution. Rain acidity in Peninsular Malaysia is on the rise and the number of areas affected by acid rain is growing. A Malaysian Meteorological Service (MMS) study shows that Malaysia is beginning to experience effects of acid rain similar to those in such industrialized countries as the United Kingdom, Japan and the United States. Areas most seriously affected by acid rain are Kuala Lumpur, Johor, Kedah and Selangor, while rain acidity in Petaling Jaya and Senai has gone up four times from 1985 to 1988.
The Malaysian Watch Acid Rain 1990 project showed that except for Malacca, Kelantan, Terengganu and Sarawak, all states in Malaysia are experiencing acid rain. Studies by the Meteorological Service Department revealed that acid rain is fast becoming an environmental problem. Acid rain is corrosive of metals such as iron and zinc roof, marble and limestone. Low pH values have been attributed to increased industrial activity and large numbers of motor vehicles emitting considerable amounts of sulphur and nitrogen compounds into the atmosphere. Acid rain is detrimental to life and life-support systems. Acidity is measured by hydrogen ion concentration, designated as pH, and is measured on a scale of 1 to 14. A pH value below 7 is acidic, and above 7 is alkaline.
Rain water of pH less than 5.6 is considered acidic. Emissions of waste gases from industries, vehicle exhausts and power generation are causes of rainwater acidity. When the pH levels of lakes and rivers fall below about 5.5, many species of fish will die, and this in turn is followed by changes in the ecosystem.