The New Straits Times, September 26, 1997
In late June, the World Health Organisation (WHO) warned in a report prepared for a special session of the UN General Assembly, that 25 per cent of preventable illnesses are caused directly by environmental degradation.
At that time the link between health and the environmental was the least of our concerns in this country. While there were those who accused WHO of exaggerating the problem, we are now facing the consequences of environmental degradation, and we all should be held accountable.
The worst perhaps is yet to come. The present situation can be likened to "walking into the heart of a flame" - it not only gets hotter but also more dangerous to the extent that death may ensue.
The London smog of December 1952 was associated with some 4,000 deaths in just one week. The circumstances may be quite different, but if we were to carry on the way we are, the message will be the same: air pollution can kill especially when it contains hazardous chemicals.
This week we will take a brief look at one of the more common atmospheric pollutants: sulphur oxides.
Sulphur oxides come from a variety of sources - fuel oil combustion, petroleum refining, and from the chemical and metallurgic industries. Most are directly released into the atmosphere. Hence, they normally occur as atmosphere contaminants like sulphur trioxide, sulphur dioxide, sulphurous acid and sulphuric acid.
Of interest is sulphur tiroxide fumes which can result in reduced visibility. Sulphur trioxide moreover, when combined with water will form droplets of sulphuric acid. Sulphuric acid itself has been known to result in further environmental and health damages especially when it turns into acid rain. Indeed during pollution episodes associated with burning, the particles are strikingly acidic.
Of greater interest however is another colourless gas, sulphur dioxide, which also reduces visibility as the result of reactions between organic compounds and nitrogen oxides to form minute particulates. How much of these substances are currently impeding visibility is still unclear.
In any case, sulphur dioxide is a severe irritant to the respiratory mucous membranes and skin, caused by the rapidness with which it forms sulphurous acid especially in a polluted environment. Its concentration too tends to increase from an average of about 0.03 parts per million (ppm) in the air or, to about 0.14 ppm as a 24-hour average.
Sulphur dioxide itself can be released into the atmosphere from another sulphur-related compound called sodium hydrosulfite when it comes in contact with acids, and through other industrial processes. It is therefore interesting to note that one of the steps outlined in the national plan to control the haze is to reduce the emission of sulphur dioxide from factories.
The experience of the London smog has shown that political will can make a big a difference. The promulgation and enforcement of the Clean Air Act of 1956 has been "so successful that smoke and sulphur dioxide concentrations in our (British) cities fell progressively through the following three decades" claimed an editorial in a recent issue of the Journal of the Royal Society of Medicine. Shouldn't we too emulate this and hasten improvement in the air that we breathe?
There is every reason that we should, since approximately 90 per cent of all sulphur dioxide inhaled is absorbed in the upper respiratory passages, where most effects are felt. A concentration up to one ppm of the sulphur fumes can cause the respiration rate to increase although there is minimal effect on the functions of the lung. Slightly more that a half this amount (1.6 ppm), increased resistance to breathing begins to occur in normal individuals. For those with respiratory problems, this is observed at an even lower reading of about 0.7 ppm. Is it any wonder why so many are now flocking to the hospitals with similar complaints?
At a higher concentration of about 10 ppm, irritation of the eyes, nose and throat are more frequently reported. In some cases choking, narrowing of the airways, (bronchoconstriction) with difficulty in breathing becomes more apparent. In a human experimental study with subjects inhaling through the mouth, brief exposure to 13 ppm caused a 73 per cent decrease in air flow to the lungs as compared to 40 per cent at five ppm. Experiments using rats showed decreased life span with accelerated ageing and heart, lung and kidney damage on uninterrupted exposure to one ppm.
In other words, in the worst case scenario, we can be chemically poisoned as the haze prolongs and worsens. It is therefore urgent that everyone understands the gravity of the situation and take all available precautionary measures so that we are not unduly exposed to the haze regardless of what the API is. Better yet, we should work even harder to eliminate all potential sources of such pollution once and for all before we regret it.
