The New Straits Times, October 10, 1997
The haze, although it has apparently abate, continues to pose many problems. The report that more policemen in the Federal Territory fell sick recently (NST, Sept 27) underscores one of the many risks faced by us un the current period of environmental degradation.
While some have the 'luxury' of staying indoors as advised, others have no choice either because of the call of duty or because they are forced to earn a living. They are the people who will have to bear the health consequences over time.
Despite the improved API readings, we are still not sure what the exact composition of the pollutants is and in what amounts. This is important because photochemical air pollution many still be around arising from a series of atmospheric reactions. The main components involved are ozone, oxides of nitrogen and other hydrocarbons.
Such gases freely seep into homes and workplaces and linger on. In any case, there is always the tendency for atmospheric conditions inside and outside the house to achieve equilibrium over an extended period unless we are boxed up in an air-tight compartment, totally cut off from the outside.
In short, breathing air containing these chemicals is like breathing poisonous gases and acids to the eventual detriment of health.
Apart from sulphur dioxide, ozone and nitrogen dioxide are the other respiratory irritant gases normally found in polluted air (NST, Sept 26). When sufficient concentrations of sulphur, nitrogen oxides and hydrocarbons build up in the atmosphere and are bombarded by sunlight, a complex series of chemical reaction takes place to create these gases.
Nitrogen dioxide, one of two commonly-found dangerous nitrogen oxides (the other being nitric oxide), can also reduce atmospheric visibility with a distinctive dark brownish haze and pungent odour. It can also be slowly converted from nitric oxide, a gas with a sharp, sweet odour.
The sources of both are nitrous and nitric acid, and reactions of nitric acid and organic materials. They are also released from burning nitrocellulose, and through industrial activities like electric arc-welding, electroplating and engraving.
In addition, oxides of nitrogen can be found in engine exhaust; nitrogen dioxide, for example, has been reported to be a good indicator of traffic activity. This is because nitric oxide produced by combustion of vehicle fuel is rapidly changed by ozone to nitrogen dioxide.
In turn, as the air containing nitrogen dioxide and organic compounds derived from vehicle exhaust drifts from areas of higher concentration, for instance, urban sources, it can take part in atmospheric photochemical reactions (that is, in the presence of sunlight) which subsequently lead to the formation of ozone. Thus, ozone concentrations tend to be spread as suburban and rural pollutants as well.
It may even drift for large distances over geographical boundaries, especially in sunny climates. Such circumstances can be further exacerbated by photochemical air pollution.
Ozone, a triatomic oxygen fume with a sharp, distinctive smell, tends to exert almost similar effects to the nitrogen oxides. In fact, ozone has been singled out as the oxidant of critical importance in polluted atmospheres.
After fine particulates from smoking, second-hand smoke, vehicle exhaust and wood burning, researchers believe ozone is the second greatest cause of lung disease affecting the terminal bronchioles and the alveolar ducts. Multiple exposure to nitrogen oxides could make the condition even worse since the sites of ozone deposition in the lungs are normally close by to those of nitrogen dioxide, both being deep lung-irritants.
Hospital admissions from acute respiratory diseases, including asthma, is said to go up when the concentration of ozone rises above 80 parts per billion (ppb). In experimental animals, a variety of toxic effects have been documented when exposes to ozone that can occur in urban areas with photochemical pollution.
Inhaling nitrogen oxides, like ozone, can cause irritability of the mucosa. Being irritant gases with relatively low water solubility, there is little upper respiratory irritation at low levels (less than 10 ppm nitrogen dioxide) initially. But on prolonged exposure, cough and nausea may develop. With more concentrated exposures, symptoms like burning eyes, sore throats, and painful coughs will begin to show.
As more gas is inhaled, the slow accumulation of nitric acid in the lungs can result in delayed onset of chemical pneumonitis, an inflammatory condition.
A progressive cough, difficulty in breathing, increase in heart beat as well as water retention in the lungs are other delayed effects. The onset is more rapid after exposure to higher concentration; it can be fatal.
Permanent restrictive and obstructive damage to lung passages may become evident following recovery of such conditions.
In other word, even if there are sings of the haze abating, we should not forget the lingering fumes that continue to haunt us. We need to find out more about this so that we can make a more informed decision in taking action to protect our health and that of our families. Failing to do so could lead to more significant ling-term consequences, even to those seemingly not exposed to the haze.
