Strolling in the rain may be poetic, but in recent years many people have given up being romantics and prefer to shelter beneath umbrellas. After all they do say acid rain can make you go bald.

Quick-witted garages have also thought up a new service by encouraging customers to fork out a few thousand NT dollars extra to get their cars treated to prevent corrosion from acid rain.

Under the electron microscope corrosion and rust due to acid rain shows up not just on cars, but also on the exterior of our houses and the surfaces of many outdoor metal objects.

There are signs that acid rain is already beginning to affect our lives, although in fact rain naturally has a weak acidity (an acid-base value of about 5.6) due to bonding with carbon dioxide in the atmosphere during precipitation. In addition acidity is present in nature, so that apart from special circumstances (for example, rain is more acidic in volcanic areas), abnormality is only suspected if an area's rain has a long-term acid-base value of less than 5 (each digit less on the scale represents a 10-fold increase in acidity).

Historically, abnormal acidity in rain was first discovered in Britain, where industrial civilization first took root, and the term "acid rain" was coined bY the British scientist R. A. Smith in 1872. But people have only begun to take a real interest in acid rain and to conduct scientific investigations into it during the past 20 years, once sufficient concern had been generated by acid rain's obvious harmful effects on the environment.

In the 1950s and '60s people began searching for natural and manmade causes for continued poor growth of forests in Scandinavia. Many countries with stunted forest growth discovered that their rain was very acidic, some with an acid-base value as low as 4. Since tree growth is closely dependent on water and soil quality, acid rain was suspected to be the principle cause of sluggish forest growth and a major acid rain research effort was launched. Scientists have established that acid rain is linked to industrial civilization. Its main constituents are sulphuric acid and nitric acid, in the form of oxides of sulphur and nitrogen (sulphur dioxide and nitrous oxide) which are formed by a complex chemical action.

Oxides of sulphur and nitrogen are emitted in gaseous form wherever coal and petroleum are widely used--such as in the combustion of petrochemical raw materials, high-temperature engines in industrial plants, power plant generators, and vehicular traffic.

The sulphuric and nitric acids in acid rain have been proved to break down the protective wax in foliage and leach the nutrients from leaves and branches, and are thus the chief culprit behind forest blight.

Forested areas readily attract clouds and rain, and trees also grow upwards, so their foliage takes the brunt of the rainfall. But rain also soaks into the topsoil and drains into lakes, producing "acid soil" and "acid lakes."

In Norway, for example, which has nearly 200,000 lakes, over half of the freshwater lakes have been found to be acidic, indirectly affecting the survival of fish and other aquatic life forms.

Chemical analysis of lake-bed sediment by German scientists has shown that this lake acidification only dates from the last hundred years and is purely due to modern industry.

What makes scientists even more worried is that acid rain can dissolve heavy metals, many of which are present in soil. Where for example aluminum is a major component of the soil, if the aluminum is dissolved it raises the concentration of heavy metal in the soil and will harm the root systems of plants. When it reaches a lake, the dissolved aluminum will turn into a granular colloid which damages the breathing systems of fish. Jing-Shiou Chen, a senior specialist in air quality protection with the ROC's Environmental Protection Administration (EPA), points out that heavy metals washed out of the soil or metal water-pipes will accumulate in the bodies of people or other living things and cannot be expelled, causing serious harm.

In addition to harming the natural environment, acid rain also threatens civilization itself. Despite its recent origin, it has already become by far the most corrosive element in the atmosphere. Many metal artifacts, marble monuments and art works in Europe are showing signs of rust, crumbling and deterioration. In particular, once stone sculptures are damaged they can never be restored.

In 1975 the director of National Central University's Environmental Center, Lu Shih-tsung, initiated an islandwide survey of Taiwan's rainfall. His project was taken up by the Taiwan Forestry Research Institute and other university research bodies, together with the EPA. Their report indicated that the rainfall in many parts of Taiwan, such as the central mountainous region, is still "clean," but the rain in the major conurbations of northern and southern Taiwan, together with certain industrial zones, is becoming more and more acidic.

Yet a number of scholars think Taiwan in some ways is very lucky because a lot of its high-atmosphere pollutants are blown away by northeasterly seasonal winds and southwesterly air currents and swept out into the Pacific. So for the time being there is still no need for Taiwan to worry about acid rain coming from far afield on high altitude air currents.

Not that this means we can rest easy, since regional acid rain may be even more serious.

Judging by analysis of acid rain samples collected at Taipei Botanic Garden since 1981 by Chin Heng-piao of the Taiwan Forestry Research Institute, the nitric acid content in Taipei's acid rain (resulting from traffic exhaust) is growing at a faster rate than its sulphuric acid content (from industrial fumes). "So Taipei's acid rain is being caused more and more by city traffic," Chin Heng-piao says.

Last year an islandwide soil survey was conducted by government agriculture departments which found that the acidbase value for arable land had fallen by 0.8. Where soil is concerned any reading below 6.5 on the scale is strongly acidic, and over 90% of Taiwan's farmland is below this level, affecting agricultural produce.

Explaining the reasons underlying soil acidification, Chang Hsueh-k'un, director of the Taoyuan Agricultural Improvement Farm, points out that in addition to factors such as the relatively high acidity of northern Taiwan's red soil, the loss of alkaline cations from the soil through heavy rainfall and the heavy use of chemical fertilizers by Taiwan farmers, "sulphurous discharges released by Taiwan's petrochemical plants are another reason why the soil is turning acidic."

Owing to improper human management, soil all over the world is becoming subject to two extremes, either increasing acidity where rainfall, population and industry are on the rise, or increasing alkalinity where rainfall, forests and population are decreasing, where plants cannot grow and where desertification is setting in.

What effect is Taiwan's acid rain having on its soil, forests and lakes? There are no answers to this question at the moment because there has been too short a history of research. But crops suspected of being contaminated by acid rain have recently been discovered near the thermal power station at Linkou, in northern Taiwan. Acidic rain has a dehydrating effect on carbohydrate, and now even the most pollution-resistant local windbreak forest is showing signs of bark dehydration. Local farmers suspect this may be due to acidic pollution caused by emissions from the Linkou power plant.

While we in Taiwan are just beginning to worry about the effects of acid rain, active countermeasures are already being adopted in Europe and America to remedy environmental acidification. Acid rain knows no boundaries and concerted action on a global scale must be taken if any effective results are to be achieved. Many research projects are now being under-taken on an international basis.

Since oxides of sulphur and nitrogen cause serious air pollution, close attention is being paid to the sulphur content in petroleum products. The EPA has already set a maximum sulphur content of 1% for petroleum products nationwide from July 1, and this will be brought down below 1% by 1993. With this in mind, China Petroleum is already building a low-sulphur oil refinery at Talin, Kaohsiung.

As far as Taipei city is concerned, the answer lies in controlling the number of vehicles on the road. Even with low-sulphur fuel, overall pollution will never be lessened unless the number of vehicles is reduced.

Unfortunately there is still no effective means of controlling the number of cars and motorbikes in Taiwan, and the Ministry of Communications has recently lowered the tariffs on imported cars. "If the number of cars and motorbikes in Taipei goes on rising, I'm afraid no one is going to believe that the air will ever improve or that acid rain can be reduced," the EPA's national acid rain supremo Jing-Shiou Chen admits with a shake of his head.

Scientists still have no answer to widespread concerns that acid rain can make you go bald. But Chin Heng-piao is sure that overexposure to acid rain certainly has its dangers. Its impact on human beings is essentially the same as on trees, it's just absorbed to a different extent.

But because acid rain doesn't harm human beings directly, most people underestimate it. Among pollution studies in Taiwan, acid rain still comes way, way behind garbage, air pollution and water pollution.

Apart from scattered sample studies on acid rain by a few individual scientists, the only analysis of acid rain by an environmental protection body is that being carried out by EPA's monitoring station at Chung Cheng Bridge, Taipei.

Although excessive rainfall brings disaster, man has always depended on rain to ensure a steady food supply. Farmers stricken by drought looked to the clouds for succour, and ancient kings made sacrifices to ensure rainfall in good season. All living things rely on rain for their existence, and rainwater is indeed the fountainhead of life. Yet if the rain itself is "sick," surely we should do all we can to make it whole again.

[Picture Caption]

Acid rain is said to make you go bald, so even those who hate carrying umbrellas can't afford to be too happy-go-lucky in the rain!

Water comes from heaven above, and if the reinwater is "sick," what will become of all those living things that depend on water for nourishment? (photo by Arthur Cheng)

Europeans concerned for the preservation of ancient monuments despair over the damage to outdoor art works done by acid rain. This photograph was taken in Paris.

The acid rain issue only gained widespread attention with the deterioration of forests in Europe. This scene was photographed in Switzerland. (photo by Arthur Cheng)

Areas adjoining industrial zones often suffer from acid rein. Shown here is a thermal power plant at Hsieho, eastern Taiwan.

Wind-driven power generation avoids emissions that cause acid rain. Wind power is used to generate electricity in California. (photo by Arthur Cheng)

Vehicle exhaust emissions are a major cause of urban acid rain.

Researchers have discovered that acid rain is responsible for corroding objects standing in the open.

Despite the lack of funding, Taiwan acid rain researchers are in good heart. A seminar on acid rain attracts full attendance. (photo by Huang Li-li)