With the degradation of the quality of our environment, the incidence of asthma is on the rise. The choking ailment seems to be acute even among children, as pointed out by recent studies in the us
it may escape one's notice, but every time we breathe, we inadvertently inhale an invisible stream of gases, aerosols, particles, microbes, pollen and dust into our lungs. Although many take it for granted, it is an act that is not easy on millions of people all over the world. The encounter with allergens, irritants, cold air or viral infections could trigger a complex series of events leading to the inflammation and constriction of the air passage. The victims of all such conditions are innocent prey to asthma, the invisible strangler. The condition, according to most researchers seems to be caused primarily due to the quality of our environment ( Environmental Health Perspective , Vol 104, No 1).
Emissions of soot and smog-forming volatile organic compounds -- which are major components of motor car exhausts -- are serious culprits. Though certain studies fail to implicate air pollution as an aggravating factor, for victims of asthma, exposure to air pollution aggravates the pre-existing malady and results in more symptoms and an even greater recourse to medications. It also means more visits to the hospital. The Harvard Six Cities Air Pollution Health Study demonstrated that the chances of contracting bronchitis increased with greater concentrations of fine particulates (particles less than 15 micrometres in diameter, a micrometre being a millionth of a metre). Another study by Douglas Dockery and C A Pope of the Harvard School of Public Health found that school children in the us revealed many more respiratory problems when fine particulate concentrations attained the air quality standard of 150 micrograms per cubic metre. One may wonder as to how fine particles -- which are almost gaseous in nature -- could provoke asthma. A common link between these fine particles is their origin -- they all source from the process of combustion whether it be from automobiles, industries, power plants or mills.
Ozone, another powerful oxidant and respiratory irritant, is the main component of smog in urban areas. Despite the strict maintenance and review of federal ozone standards, the American Lung Association estimates that the health of two million children under 18 is potentially prone to asthma. Irritation of the bronchi by pollutants like ozone could make it easier for antigens to penetrate the airway lining and reach lymphocytes and other cells involved in the allergic response.
Other pollutants like sulphur dioxide, the main component of acid aerosols and nitrogen dioxide (an indoor pollutant from gas stoves or even pollen grains), clearly exacerbate asthma. They irritate the cells lining the airways and increase sensitivity to inhaled allergens. It may come as a surprise but it is a fact that exposure to 'indoor allergens' could also cause an alarming hike in the incidence of asthma. Allergen levels are thought to be higher in homes which are not very well-ventilated, in which moisture levels are higher, allowing mildew and moulds to thrive. Research also shows that cumulative exposure to dust which are found in bedding, upholstery and carpets, causes some people to develop allergic sensitivity, including asthma and airway hyper-responsiveness. The levels of the 'cockroach antigen' in certain urban dwellings are also enough to cause sensitisation. They too appear to be intimately associated with asthma.
Passive smoking is also related to the occurrence of asthma. Alfred Munzer, a pulmonary specialist at Washington d c's Adventist Hospital and former president of the American Lung Association, opines: "There is increasing evidence that childhood exposure to environmental smoke can be a predisposing factor to developing asthma." Infants born of mothers who smoke have higher levels of antibody immunoglobulin e compared to infants of non-smokers, indicating an immune reaction. A 1990-study published by the British Medical Journal stated that the increase in the number of asthma patients in Western nations was related to the increase in the number of smokers among women of childbearing age.
Largescale studies are being undertaken to understand the disease better. The National Inner City Asthma Study is underway in seven American cities to identify the various factors which most definitely provoke an asthma attack among its sufferers. In the second phase of the study, researchers plan to develop methods by which people with asthma can alleviate themselves from episodes of the disease. They also plan to recommend ways by which to reduce dust mites and cockroaches and evaluating allergy symptoms and lung function in children who are susceptible to recurrent wheezing. Organisations like National Heart, Lung and Blood Institute jointly organised the National Asthma Education Programme which educates people about asthma. Research suggests that education to control exposure to allergens and improve urban air quality can check asthma.
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