Railway Science (Environment – Pollution)

Chlorofluorocarbons (CFCs) are organic compounds composed of carbon, chlorine, and fluorine. They are used in aerosols, refrigerators, and air conditioners. These are responsible for global warming. Ozone depletion causes skin cancer, cataracts, and impaired immune systems. Montreal Protocol (1987) - To protect the ozone layer.

This is because vehicles traveling along our roads throw dust into the air. This mixes the pollen and makes it airborne, which allows it to come much more easily into contact with your eyes, nose and throat. Hay fever: It can cause sneezing, a stuffy or runny nose, watery eyes, and itching of the nose, eyes or the roof of the mouth.

The electrostatic precipitator works by removing particles and smoke from a gas stream using an electrostatic charge. It is a type of filter (dry scrubber) that uses static electricity to remove soot and ash from exhaust fumes before they exit the smokestacks.
Other pollution control techniques - Noise pollution (Acoustic barriers, Soundproofing materials); Visual pollution (Landscaping and greenery); Water pollution (Coagulation and flocculation, Filtration system).

Category of Area : Industrial (Limits in Day Time - 75 db, Limits in Night time - 70 db), Commercial (Limits in Day Time - 65 db, Limits in Night time - 55 db), Residential (Limits in Day Time - 55 db, Limits in Night time - 45 db), Silence Zone (Limits in Day Time - 50 db, Limits in Night time - 40 db). Sound-level meter - Device for measuring the intensity of noise, music, and other sounds.

Catalytic converters work by using the catalyst (Platinum, Palladium, and Rhodium) to speed up a chemical reaction that converts harmful gasses into less harmful substances. The main pollutants that are converted by catalytic converters - Carbon monoxide, Nitrogen oxides, Unburned hydrocarbons, Carbon dioxide.

Ammonia (NH₃) - It is an inorganic compound of nitrogen and hydrogen. Properties :- Colourless gas, a strong and pungent odour. Uses :- Used as refrigerant gas, for purification of water supplies, and in the manufacture of plastics, explosives, textiles, pesticides, dyes and other chemicals.
Black carbon (C) :- Sooty black material emitted from gas and diesel engines, coal-fired power plants. Methane (CH₄) :- It is also a greenhouse gas.

Asbestos - refers to a group of naturally occurring minerals composed of fine, durable fibres that are resistant to heat, fire, and various chemicals. Mineral Families of Asbestos : Serpentine asbestos - It has curly fibres made up of sheets of crystals. The single type of asbestos from the serpentine family is chrysotile. Amphibole asbestos - It has needle-shaped fibres. Example - Amosite and crocidolite.

Fluoro carbon - Organic compounds that contain carbon and fluorine. They are also known as perfluorinated compounds. Uses - refrigerants, lubricants, non-stick coatings, medical devices and in the manufacture of plastics.
Carbon monoxide (CO) - An odorless, colorless gas formed by the incomplete combustion of fuels. Sulfur dioxide (SO₂) - A gaseous air pollutant composed of sulfur and oxygen.

Catalytic converter : A device incorporated in the exhaust system of a motor vehicle, containing a catalyst for converting pollutant gases into less harmful toxic Pollutants. Carburetor : A device for supplying a spark-ignition engine with a mixture of fuel and air.
Inverter : A power electronic device or circuitry that changes direct current (DC) to alternating current (AC). Radiator : An engine-cooling device in a motor vehicle or aircraft consisting of a bank of thin tubes in which circulating water is cooled by the surrounding air.

The Comprehensive Environmental Pollution Index (CEPI) - It is developed by the Central Pollution Control Board (CPCB). Classification of CEPI scores out of 100 :- > 70 and above - Critically Polluted Areas, 60 to 70 - Severely Polluted Areas and less than 60 - Normal Polluted Areas.