Respiratory system is in direct contact with the atmosphere- the air. Therefore, many respiratory problems can occur due to air pollution, although several other environmental factors could also contribute. Although the skin is the outermost part of human body in contact with atmospheric air, it is shielded (or can be protected) to a large extent by clothing. The lungs however cannot be protected from air – they have to breathe in the air.
There are quite a few differences in the outdoor and indoor environmental air pollution. Outdoor pollution of importance to the lungs is mostly caused by gaseous and particulate exhausts from industry, automobiles, quarries, mines, dusts and storms. Indoor pollution on the other hand results from domestic combustion of soled biomass fuels such as the dried animal dung, forest-wood and crop-residue. Some other indoor air pollution include environmental tobacco smoke, vapours of volatile materials, micro-organism, fungi, molds, insecticides and sprays (etc.). Although most of the indoor pollutants are also present in the outdoor air, the exposure is relatively minor in view of the significant dilution of their concentrations in the open environment.
It is commonly seen in people living in relatively close-door, poorly ventilated houses and flats of multi-storeyed building. Residents may suffer from fatigue myalgia, irritability, headaches and generalized lethary. Depression is another common problem faced by some people. It results from cumulative action of a multitude of indoor atmospheric pollutants.
Dry irritating cough which can sometimes be severe, throat irritation and phlegm
production are common. Watering of eyes and nose is also frequent.
Persistent exposure to air pollutants causes chronic inflammations of trachea-bronchial tree i.e. chronic bronchitis and chronic obstructive pulmonary disease (COPD). Chronic cough, sputum production, breathlessness and recurrent respiratory infections occur as a result of COPD. Progressive disease may lead to respiratory disability and failure. These effects are especially common in elderly individuals and smokers.
Air pollution is an important cause of precipitation of an acute attack of asthma. Asthmatic patients living in polluted environments suffer from more persistent disease and require greater amount of drugs for control of their symptoms. They also have more frequent exacerbations, infections, emergency visits and hospitalization. This is also true for children and other non-smoking asthmatic patients who get exposed to environmental tobacco smoke (passive smoking) from smoking of parents, spouses or colleagues.
Exposure to air containing infective organisms causes respiratory infections. These include both viral and bacterial upper respiratory catarrh and pneumonias. Tuberculosis similarly occurs due to infection with the tubercle bacilli. Young children and the older people with immune – deficiencies and other diseases are specially prone to develop both pneumonias and tuberculosis due to weakening of their defense system.
Inhalation of organic dusts cause diseases such as hypersensitivity pneumonias. Farmers’ lung, bird-fancier’s lung, mushroom picker’s lung, byssinosis and baggasosis are some of the examples where people engaged in a particular profession and thus exposed to the occupational allergens develop hyper-sensitivity diseases.
Inroganic dusts such as silica, coal and asbestos get deposited in the lungs of workers at the quarries, mines and industrial units. They may therefore suffer from different occupational inorganic dust diseases or pneumoconiosis. Continued exposure leads to progressive respiratory impairment and death.
Inhalation of gases and metal fumes may cause acute respiratory effects such as gaseous intoxication and metal fume fever. Toxic gas inhalation may cause cyto-toxicity and even death.
Several other environmental pollutants are injurious to lungs and may cause lung fibrosis and cancers. Tobacco smoking is considered as one of the most important pollutant which releases over 4000 chemical substances in the air. It is an important cause of lung cancer. Similarly, heavy metals such as arsenic, chromium and nickel are also carcinogenic. Asbestos causes both pulmonary fibrosis and lung cancer. Silica is an important fibrogenic agent.
To summarise, air pollution is an important cause of both chronic and acute respiratory problems. Some of the occupational diseases are seen in people specifically exposed to occupational and environmental pollutants. Nonspecific general air pollution on the other hand, affects every exposed individual and remains perhaps the most important cause of respiratory disorders.