Polluted air


The suffocating dust and smoke of our towns/cities, horrifying sight of naked hills denuded of greenery, points to the fast deteriorating environment around us. While there is undoubted increase in the comforts and luxuries in the privacies of well maintained homes, one has to go farther and farther from human habitations to breathe in unspoiled atmosphere. The environmentalists are getting shriller and shriller in their indictments of authorities encroaching upon the virgin forests and secluded hills in the name of development. They do get a sympathetic hearing in academic and even some governmental fora, but the pressure of development process is not able to dissuade the authorities from going ahead with the exploitation of hither to protected biomass in hills and forests. The loss of forests, fertility of soil, productivity and energy crisis have created many problems. The pollution created by industry, technology and over-consumption by the affluent society lead to the rapid depletion of basic natural resources. The ecological state of biosphere is becoming more and more imbalanced day by day due to technological and industrial advancements as well as population explosion. Environmental problems are so diverse and diffused that virtually every activity of civilization interacts with the environment. The addition of extraneous materials or energy in a particular environment in concentrations greater than normal renders the environment partially or wholly unfavourable for human life. Atmospheric particles form one of the most important types of pollutants due to their scattering and absorption of light, nucleation of condensation, catalysis of atmospheric pollutant reactions and hazards to health. Fog, mist, dust and soot are all forms of particulate matter. Particles are most often distinguished by their size and physical state (solid or liquid). The size of a particle is usually taken to be the diameter of a circle with the same area as the projected area of a particle seen under a microscope. Particulate matters in environment are generally contributed by dust from various sources, fibre materials of plant and animal origin, fine particles of fly ash derived from combustion of coal, from mining and processing operations carried to obtain metals. Similarly the brick kilns, stone crushers, road traffic, loading and transportation all contribute to particulate pollution and air quality degradation. Dust fall creates local problems usually in the vicinity of their source of origin. The situation in Dimapur is ample evidence of particulate pollution exceeding the permissible limits. The brick kilns and stone crushers here have affected human life, plant life and animals adversely. The particles of 10 milimicron size remain suspended and hence are called suspended particulate matters (SPM). Smaller than these SPM are respirable particulate matters (RPM) which due to their minute size can enter the human lungs up to alveolar spaces and cause different respiratory ailments like bronchitis, cancer, fibrosis, ulcers and tuberculosis. Solar radiations lower down the earth’s temperature which at times disturbs local weather conditions, pressure patterns, precipitation, etc. The photosynthetic efficiency of green vegetation of the area involved may be affected. Aerosols provide a suitable nucleus or locus on which vapours in atmosphere condense and this accelerates precipitation. The entire aerosol content of atmosphere may be brought down by rains, dew or snow. Thus acid rain, fog or smog or oxidizing type of pollution is caused. Some of the aerosols are potential carcinogenic agents. Inhalation of such particles irritates lungs and exposure for longer duration causes scarring or fibrosis in alveolar lining. Tuberculosis is one such disease which occurs quite frequently in dusty, dirty and clouded cities. Particulate pollution has become a major problem of urban areas due to addition of substantial number of vehicles daily in cities, transportation, loading, crushing, construction, poor condition of roads and other anthropogenic practices. Keeping in view the deterioration of air due to particulate pollution, it is necessary that appropriate technology be used for collection of particulates before they are emitted in to the atmosphere.