The UN Conference of Parties on climate change in 2011, was held in Durban, South Africa.
It aimed at decrease of pollutant emission.
Biochemical oxygen demand or BOD is the oxygen required for microbial decomposition of a unit mass of organic remains.
The degree of impurity of water due to organic matter is measured in terms of BOD.
A higher BOD of a river indicates that water is highly polluted.
Rachel Carson's book 'Silent Spring' reveals the harmful effect of DDT, a fatal pesticide.
The writer opposed to chemical industry in U.S.A.
This book influenced the national policy over pesticide use in many countries all over the world.
Ultraviolet radiations are of three types-UV-C (100 - 280 nm), UV-B (280 - 320nm) and UV-A (320 - 390nm).
Shorter ultraviolet radiations (UV-C) are absorbed by the atmosphere.
The longer ones (UV-A) are not much harmful.
The intermediate or UVB are harmful as well as capable of deep penetration.
Thinning of ozone layer increases the amount of UV-B radiations reaching the earth.
UV-B radiations damage skin cells, cause ageing of skin, skin cancer and eye damage.
The ozone (O 3 ) found in upper part of the atmosphere, i.e., Stratosphere, is Good ozone, since, it acts as a shield for absorbing UV-radiations from sun.
Lichens are very good pollution indicators, they do not grow in pollutted areas.
They are sensitive to sulphur dioxide pollution.
Dust separation is carried out by scrubbers.
They are of two types, dry and wet.
Both can be used to separate particulate matter by passing through dry or wet packing material but more commonly they are employed in removing gaseous pollutants like SO 2 .
Particulate matter consists of soot, flyash, dust, spores, pollen grains etc.
Particulate matter is differentiated into settleable (larger than 10 mm and remaining in air for less than one day) and suspended (less than 10 mm and remaining in air for more than one day to several weeks).
Particles of 2.5 µm and lesser diameter (PM 2.5) are the most harmful to human health (as per Central Pollution Control Board or CPCB).
They pass deep into the lungs causing breathing and respiratory problems, irritation, inflammation and damage to lungs resulting in premature death.
It cannot directly enter circulatory system but indirectly through respiratory system.
International conference held in Kyoto, Japan obtained commitments from different countries for reducing overall green house gas emissions at a level 5% below than that in 1990 by 2008-2012.
In Doha, Qatar on 8 th December 2012, the "Doha amendment to the Kyoto Protocol" was adopted.
The second commitment period is from 1 st January 2013 to 31 st December 2020.
Carbon dioxide is a greenhouse gas with warming effect of 60%.
Greenhouse gases are essential for keeping the earth warm and hospitable.
They prevent a substantial part of long wave radiations emitted by earth to escape into space and radiate a part of this energy back to the earth.
The phenomenon is called greenhouse flux.
Because of greenhouse flux, the mean annual temperature of earth is 15°C.
Recently the concentration of greenhouse gases has started rising that is resulting in increasing the mean global temperature.
It is called global warming.
Deforestation has reduced carbon dioxide assimilation.
The excess remains in the air.
Excessive use of fossil fuel is adding more CO 2 to atmosphere.
This causes greenhouse effect.
