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Source- vehicular emissions, incomplete burning of carbon based fuels, forest fires,
industrial processes , coal mining, refining of petroleum etc.
Health problems- lower the dissolution of O2 in our blood, drowsiness and
Over exposure affects vision and cause cardiovascular disorders.
Preventive measures- Developing more efficient internal combustion.
Using CNG and LNG
Source- Burning of fossil fuels, vehicular emissions industrial processes etc.
Health Problems- Hinders the respiratory processes, if present in excess.
Environmental problems- green house gas responsible for causing global
Preventive measures- CNG and LNG.
Sources- Air- conditioners and refrigerators.
Problems- Ozone layer depletion.
Sources- Fuels, batteries, paints , dyes etc.
Health problems – Damage nervous system especially in children.
Sources- Industrial and vehicular discharge.
Health problems- Watering and burning of eyes .
Oxides of Nitrogen
It incude NO, N2O and NO2
Sources- Burning of fuels, explosives, fertilizers and nitric acid.
Environmental problems – Smog and acid rain.
Health problems- respiratory diseases, bronchitis.
Preventive measures- Using catalytic convertors.
Suspended particulate matters
These include small particles like smoke and dust or liquid droplets, having size
ranging from 0.002 microns- 500microns.
Inorganic particulate matters- metal oxides
Organic particulate matters- polycyclic hydrocarbons such as chrysene.
Health problems- oxides of lead, cadmium, mercury etc. causes respiratory problems.
Certain particulate accelerate metallic corrosion and damage the buildings.
Aerosols such as smoke, fog, dust lower visibility.
Oxides of Sulphur
Include sulphur dioxides and sulphur trioxide.
Sources- Volcanic erruptions, industrial processes, vehicular emissions.
Environmental effects- Causes acid rain, smog and effect marble buildings.
Health problems- Effect respiratory tarct and cause lung diseases.
Preventive measures- Removal can be done by combustion, using chemical
scrubbers like calcium carbonate that react with sulphur dioxide to form less
harmful calcium sulphate.
BOD- It is the amount of water required by aerobic micro
organisms for biochemical decomposition process. It measures the
amount of oxygen consumed by micro organisms as they break
down organic matter within small water samples.
BOD high then dissolved oxygen content is too low to support life of
When BOD is low then dissolved oxygen is more.
For polluted water BOD will be high and for non polluted water it
will be less.
COD -It is the amount of oxygen consumed in
oxidation of organic and oxidizable inorganic material
present in water sample.
Treatment of Sewage
• It consists of three steps:
1. Primary treatment
2. Secondary treatment
3. Tertiary treatment
• The first step consists of screens, grit removal, oil and grease
trap and primary sedimentation.
Screens: The influent sewage water passes through a bar screen
to remove all large objects like cans, rags, sticks, plastic packets
etc. carried in the sewage stream
Grit removal: It includes a sand or grit channel or chamber,
where the velocity of the incoming sewage is adjusted to allow
the settlement of sand, grit, stones, and broken glass. These
particles are removed because they may damage pumps and
Oil & grease trap: Removal of oil and grease.
Primary Sedimentation: Gravitational settlement of suspended
and colloidal particles denser than water.
• It consists of biological treatment for the removal
of organic matter. Use microorganism to
decompose organic waste. After several hours
bacteria are allowed to settle down as secondary
• The sludge is further treated in 'sludge digesters':
large heated tanks in which its chemical
decomposition is catalysed by microorganisms.
• Complex biological and chemical process
removes the remaining pollutants like
minerals, metals and viruses.
Problem with Sewage water treatment
• Disposal of sludge,
• Treatment of sludge is costly and time
The unwanted noise dumped into the atmosphere that leads to discomfort
and health hazards is known as noise pollution.
Sources of Noise Pollution
•Natural phenomena such as violent volcanic eruptions,
thunder, fierce storms, etc.
•Domestic appliances such as mixers, washing machines,
• Industries such mills and
•Trains, ships, and aircrafts
•Bursting of crackers and playing
loud music during social
gatherings and festivals
• Entertainment devices
such as radio, television, etc.
The decibel (dB) is a logarithmic unit used to express the ratio
between two values of a physical quantity, often power or intensity
. One of these quantities is often a reference value, and in this case
the decibel can be used to express the absolute level of the