Introduction
The Environment can be defined as the physical surrounding of man of
which he is a part and on which he is dependent for his activities like
physiological functioning, production and consumption. His physical environment stretches from air,
water and land to natural resources like energy carriers, soil and plants,
animals and ecosystems. For urbanized
man, a large part of his environment is man made. But, even then, the artificial
environments (building, roads)
and implements ( clothes, automobiles) are the result of an input of both
labour and natural resources. Commonly
the term ‘Environment’ is restricted to ambient environment. In that view, the indoor environment (home,
work place) is regarded as isolated piece of environment to be treated on its
own terms.
The indoor environment usually is under the jurisdiction of the Public
Health authorities. Health risks are
mainly linked to space heating, cooking and lighting: low grade fuels,
insufficient ventilation, and low or non-existing chimneys are often the main
problems. Additionally, there may be
problems connected with moist, light, incidence, hazardous substances from
building materials, lacquers and paints.
Problems with drinking water, sewage and waste are not linked to the
dwelling as such, but rather due to a lack of appropriate infrastructure. Statistics on indoor environment may be
regarded as a subset of statistics on human settlements and the urban
environment.
1.1 Development
versus Environment Degradation
Development activities are measured in terms of national products which
in turn are defined as production of goods and services during accounting
period. However, certain environmental functions which are crucial for economic
performance and generation of human welfare such as provision of natural
resources to production and consumption activities, waste absorption by
environmental media and environmental services of life support and other human
amenities, are taken into account only partly in conventional accounts. The
scarcities of natural resources now threaten the sustained productivity of the economy and economic production and
consumption activities. These
activities impair environmental quality by over loading natural sinks with
wastes and pollutants. The private and
social costs of the use of the natural resources and the degradation of the
environment may be taken into account for the sustainable development in the conventional
accounts.
TABLE 1.1.1 :SOME IMPACTS OF DEVELOPMENT ACTIVITIES ON
ENVIRONMENT
|
Development
activities |
Major
impacts on environment |
|
Forest
clearing and land resettlements |
Extinction of rare species of flora and fauna,
creation of condition for mosquito breeding leading to infectious diseases
such as malaria, dengue etc. |
|
Shifting
cultivation in upland agriculture |
Soil erosion in upland areas, soil fertility
declines due to shorter cultivation cycle which is practiced due to
population pressure, flooding of low land areas. The problems could be
resolved by terraced cultivation. |
|
Agro
industries |
Air pollution due to burning of bagasse as fuel in
sugar mills, large amount of highly polluting organic wastes, surface water pollution. |
|
Introduction
of new varieties of cereals |
Reduction of genetic diversity of traditional
monoculture resulting in instability, danger of multiplication of local
strains of fungus, bacteria or virus on new variety |
|
Use
of pesticides |
Organism develop resistance and new control
methods are needed (e.g. in malaria, widespread use of dieldrin as a
prophylactic agent against pests of oil palms made the problem worse),
creation of complex and widespread environment problems. The pesticides used
in agriculture sometimes go into food chain or in water bodies and as such
results in harmful health hazards. |
|
Timber
extraction |
Degrades land, destroys surface soil, reduces
production potential of future forests. |
|
Urbanisation
and industrialization |
Concentration of population in urban centers make
huge demands on production in rural areas and put pressures on land, air and
water pollution. |
|
Water
resource projects, e.g. Dam, extensive irrigation |
Human settlement and resettlement, spread of water borne diseases, reduction of fisheries,
siltation, physical changes e.g. temperature, humidity. |
-3-
1.2 EMISSIONS,
DISCHARGES AND THEIR SOURCES
The environmental stress caused by developmental activities emanates from emissions and discharges of various substances into air, water and soil. These emissions and discharges have not only local but regional and global effects also.
TABLE 1.2.1 : LOCAL, REGIONAL AND GLOBAL EFFECTS OF
POLLUTION
|
Local effects |
Regional |
Over marine water and continents |
Global |
|
Heavy metals in air, soil and plants, e.g. From industrial emissions and Discharges Noise, Smell ,Air pollution. |
Eutrophication, Contaminants in the soil, Landscape changes, due to mining or agriculture. |
Eutrophication Acidification Environment Contaminants Radioactivity |
Changes of the climate due to ozone depletion and the greenhouse effect. |
Acidifying
emissions
Sulphur dioxide and nitrogen oxides emitted into the air are converted into acids. At their deposition they have an acidifying effect on soil and water. The emission of ammonia also contributes to the acidification. Main sources of sulphur dioxide are burning of Sulphur containing fuel like coal power stations and oil by vehicles, and refining of oils in refineries.
Emissions of volatile organic substances
Volatile organic substances might have health effects. Many of them are carcinogenic. In combination with nitrogen oxides and in sunlight , some of them might form ozone and other photochemical oxidants. These are harmful to plants.
Gases effecting the climate
The greenhouse gases ( carbon dioxide , methane etc.) prevent some of the heat radiation from the earth from escaping into space. The concentration of green house gases is increasing which is presumed to raise the temperature of the earth in a long perspective. Eighty percent of the effect of the greenhouse gases is caused by carbon dioxide.
Eutrophicating
discharges into water
Nutrients, mainly
nitrogen and phosphorus contribute to the eutrophication of lakes, rivers and
marine waters. Approximately half of
the nitrogen discharges is estimated to originate from agricultural land. A considerable proportion of the phosphorous
discharge derives from waste water not passing through sewage treatment plants.
In addition to discharges from human activities there is a natural leaching
from various types of soil. The
quantities are estimated to be of about the same magnitude as those originating
from human activities.
Emissions
of heavy metals
Discharges and emissions of heavy metals are difficult to estimate. A large proportion of emissions/discharges of heavy metals into air originates from the iron and steel industry. Road traffic is the main source of lead emissions. Mines and mining wastes account for the major part of the discharges of heavy metals into water. Cadmium depositions also originate from commercial fertilizers containing phosphorus.
TABLE 1.2.2 : SOME MAJOR POLLUTANTS AND THEIR SOURCES
|
Pollutant |
Source |
|
Carbon monoxide |
Incomplete fuel combustion ( e.g. two stroke engine) |
|
Sulphur dioxide |
Burning of sulphur containing fuel like coal in power plants and oil by vehicles |
|
Suspended particulate matter |
Smoke from domestic, industrial and vehicular sources. |
|
Oxides of nitrogen |
Fuel combustion of motor vehicles, power stations and furnaces |
|
Volatile hydrocarbons |
Partial combustion of carbonaceous fuels (two stroke engines, industrial processes, disposal of solid wastes). |
|
Oxidants and ozone |
Emissions from motor vehicles, photochemical reactions of nitrogen oxides and reactive hydrocarbons |
|
Lead |
Emissions from motor vehicles |
TABLE 1.2.3 :
POLLUTANTS AND THEIR RELATED HEALTH
HAZARDS
|
Pollutants |
Health
effects |
|
Carbon Monoxide ( from gasoline cars, 2-wheelers, 3-wheelers) |
Fatal in large does: aggravates heart disorders; effects central nervous system; impairs oxygen carrying capacity of blood |
|
Nitrogen Oxides (NOx) (from diesel vehicles) |
Irritation of respiratory tract |
|
Ozone |
Eye, nose and throat irritation; risk asthmatics, children and those involved in heavy exercise |
|
Lead ( from petrol vehicles) |
Extremely toxic: effects nervous system and blood; can impair mental development of children; causes hypertension |
|
Hydrocarbons (mainly from 2-wheelers and 3-wheelers) |
Drowsiness ,eye irritation, coughing |
|
Benzene |
Carcinogenic |
|
Aldehydes |
Irritation of eyes, nose and throat, sneezing, coughing, nausea, breathing difficulties; carcinogenic in animals |
|
Polycyclic Aromatic Hydrocarbons PAH (from diesel vehicles) |
Carcinogenic |