Posted By: Foram Desai, Ecochem Sales and Services, Surat
Air pollution is an outcome of the global industrialization trends. The air that sustains life i.e. has life supporting properties has life damaging properties too. Ideally, the air is a balanced mixture of the gases within the atmosphere. But when the balance is disturbed i.e. the air is polluted, it may affect the human health. Statistically an average man breathes 22,000 times a day and takes in 16 kg of air. The effect worsens during winter season especially in cold countries. During winter, the pollution level is at the peak, since the pollutants are highly concentrated at the ground level.
All the impurities/pollutants in air do not necessarily affect human health. The prime factors affecting human health are as follows:
- Nature of the pollutants
- Concentration of the pollutants
- Duration of exposure
- State of health of receptor
- Age group of the receptor
The susceptibility to air borne health effects are high in infants and children. Also, people with chronic diseases of the lungs or heart are at a greater risk. Many major air pollution disasters in major industrial towns and cities have occurred till date; Meuse valley, London, New York, Bhopal, etc. Of which three events have been noted in New York city and four in London owing to the industrial revolution.
Health Effects of Air Pollutants on Human Health
Effects of the pollutants generally occur as a result of contact between the pollutants and the body. Bodily contact occurs at the skin surfaces and other membranes. Contact with the exposed membranes is considered more harmful due to their absorptive capacity. Pollutants like air-borne gases, vapors, fumes, mist and dust may cause irritation in the respiratory as well as the digestive tract.
- Eye, nose and throat irritation
- Irritation of the respiratory tract
- Odour nuisances due to certain gases
- Asthamatic effects
- Chronic pulmonary diseases
- Cardiovascular and heart problems
- Flourosis and mottling of teeth
- Carcinogenic effects
- Respiratory diseases
- Occupational diseases like silicosis, asbestosis.etc
Effects of Specific Pollutants:
- Sulphur dioxide: Sulphur dioxide is an irritant gas affecting the membranes on inhalation. Certain specific conditions lead to oxidation of dioxide to trioxide. The gases further, in presence of water and water vapor forms sulphurous and sulphuric acids respectively. Sulphur trioxide is severe irritant causing severe bronchospasms at relatively lower levels too.
- Carbon Monoxide: Carbon monoxide is a member of the carbon oxides group. It has higher affinity towards haemoglobin of the blood to form carboxyhaemoglobin, COHb. Generally, the function of haemoglobin in the human blood is to transfer oxygen to the cell tissues. On entering human body, carbon monoxide has 200 times higher affinity than oxygen to combine with the haemoglobin. Thus, lower levels of Carbon monoxide can also prove to be inducing harmful effects on the human body. Carbon monoxide also severely affects the nervous system. It reduces the blood circulation and thus increases the risk of heart attacks.
- Oxides of Nitrogen: Of the seven oxides known to exist, only two of the nitrogen oxides are harmful to the human health; the nitric oxide (NO) and nitrogen dioxide (NO2). Nitrogen dioxide is known to cause occupational disease. Among occupations with NO2 hazards are the manufacture of nitric acid, exposures of farmers to sillage that has had high nitrate fertilization, electric arc welding and mining utilizing nitrogen compounds as explosives. Eye and nasal irritation are also observed after exposure to about 15 ppm of nitrogen dioxide and pulmonary discomfort after brief exposures to 25 ppm of nitrogen dioxide.
- Hydrogen sulphide and mercapton: Hydrogen sulphide is a foul smelling gas, irritant to the nasal tract. It has typical smell like that of a rotten egg. Frequent short term exposures to the gas may also cause fatigue to the sense of smell. Sulphur and its other compounds exhibit only odour nuisance to the human nose. No other health effects have been reported.
- Ozone: On inhalation, ozone is likely to disturb, affect and irritate the respiratory tract due to the inhibition to oxygen reaching the lungs.
- Flourides: Flourides present in air may be corrosive like hydrogen fluoride or may be non reactive. Flourine is reported to have cumulative effects on prolonged exposures even in minutest concentrations.
- Lead: Lead is generally emitted from automobiles and its concentrations are high in urban areas with heavy traffic density. Inorganic lead causes health effects like gastro internal damage, liver and kidney damage, abnormalities in fertility and pregnancy, also affecting mental health of children.
- Hydrocarbon vapors: Hydrocarbon vapors are sources arising from chemical vapor clouds, industrial release, etc. The effects of hydrocarbon vapors on human health includes irritation to the eyes and respiratory tract. Photochemical smog is also a potential source trapping hydrocarbon vapors. Incomplete combustion of hydrocarbons may result in formation of poly cyclic organic compounds which are carcinogenic in nature.
- Particulate matters: The air apart from the above gases and vapors is also comprised of small microscopic matters. These matters when come in contact with the exposed membranes may cause irritation in the eyes, respiratory tract, diseases of digestive tract, infection in the digestive organs. Many of these microscopic agents are organic in nature like pollen, yeasts, moulds, animal hair/fur, etc. These allergens may be allergic to the skin as well as respiratory tract.