`star` Pollution
`star` Harmful Effects of Air Pollution
`star` Control of Air Pollution
`star` Air pollution due to Automobiles


● `color{violet}("Human population size")` has `color{violet}("grown enormously")` over the last hundred years.

● This means increase in `color{violet}("demand")` for `color{violet}("food, water, home, electricity, roads, automobiles")` and numerous other commodities.

● These `color{violet}("demands")` are exerting `color{violet}("tremendous pressure")` on our `color{violet}("natural resources")`, and are also `color{violet}("contributing")` to `color{violet}("pollution")` of `color{violet}("air, water")` and `color{violet}("soil.")`

● The need of the hour is to check the `color{violet}("degradation")` and `color{violet}("depletion")` of our precious `color{violet}("natural resources")` and `color{violet}("pollution")` without halting the process of development.

● `color{brown}("Pollution")` is any undesirable change in `color{violet}("physical, chemical")` or `color{violet}("biological characteristics of air")`, `color{violet}("land, water or soil")`.

● Agents that bring about such an undesirable change are called as `color{brown}("pollutants")`.

● In order to control `color{violet}("environmental pollution,")` the Government of India has passed the `color{brown}("Environment (Protection) Act, 1986")` to protect and `color{violet}("improve the quality")` of our environment `color{violet}("(air, water and soil)")`.


● We are dependent on `color{violet}("air")` for our respiratory needs.

● `color{violet}("Air pollutants")` cause injury to all `color{violet}("living organisms.")`

● They `color{violet}("reduce growth")` and `color{violet}("yield of crops")` and cause premature `color{violet}("death of plants.")`

● `color{violet}("Air pollutants")` also deleteriously affect the respiratory system of `color{violet}("humans and of animals.")`

● Harmful effects depend on the concentration of `color{violet}("pollutants,")` duration of exposure and the organism.

`star` `color{green}("PM 2.5")`

● Recently we have realised the `color{violet}("dangers of particulate matter")` that are very very small and are not removed by the precipitators.

● According to `color{violet}("Central Pollution Control Board (CPCB),")` `color{brown}("particulate size 2.5")` micrometers or less in diameter (`color{brown}("PM 2.5")`) are responsible for causing the greatest harm to `color{violet}("human health.")`

● These fine particulates can be inhaled deep into the `color{violet}("lungs")` and can cause breathing and respiratory symptoms, irritation, inflammations and damage to the `color{violet}("lungs")` and `color{violet}("premature deaths")`.


● Smokestacks of `color{violet}("thermal power plants, smelters")` and other industries release particulate and `color{violet}("gaseous air pollutants")` together with harmless gases, such as `color{violet}("nitrogen, oxygen, etc.")`

● These `color{violet}("pollutants")` must be separated/ filtered out before releasing the harmless gases into the atmosphere.

`star` `color{green}("Electrostatic Precipitator")`

● There are several ways of `color{violet}("removing particulate matter")`; the most widely used of which is the `color{brown}("electrostatic precipitator")`, which can remove over `color{violet}(99%)` particulate matter present in the exhaust from a thermal power plant.

● It has `color{violet}("electrode")` wires that are maintained at several thousand volts, which produce a corona that releases electrons.

● These `color{violet}("electrons")` attach to dust particles giving them a `color{violet}("net negative")` charge.

● The `color{violet}("collecting plates")` are grounded and attract the charged dust particles.

● The `color{violet}("velocity of air")` between the plates must be low enough to allow the dust to fall.

`star` `color{green}("Scrubber")`

● A `color{brown}("scrubber")` can remove gases like `color{violet}("sulphur dioxide.")`

● In a `color{violet}("scrubber")`, the exhaust is passed through a spray of `color{violet}("water or lime. ")`


● `color{violet}("Automobiles")` are a major cause for atmospheric `color{violet}("pollution")` atleast in the metro cities.

● As the number of `color{violet}("vehicles increase")` on the streets, this problem is now shifting to the other cities too.

● `color{violet}("Proper maintenance")` of `color{violet}("automobiles")` along with use of `color{violet}("lead-free petrol or diesel")` can reduce the `color{violet}("pollutants")` they emit.

`star` `color{green}("Catalytic Convertors:")`

● `color{brown}("Catalytic converters")`, having expensive metals namely `color{violet}("platinum-palladium")` and `color{violet}("rhodium")` as the catalysts, are fitted into `color{violet}("automobiles")` for reducing emission of poisonous gases.

● As the exhaust passes through the `color{violet}("catalytic converter, unburnt hydrocarbons")` are converted into `color{violet}("carbon dioxide")` and `color{violet}("water,")` and `color{violet}("carbon monoxide")` and `color{violet}("nitric oxide")` are changed to `color{violet}("carbon dioxide")` and `color{violet}("nitrogen gas")`, respectively.

● `color{violet}("Motor vehicles")` equipped with `color{violet}("catalytic converter")` should use unleaded petrol because lead in the petrol inactivates the `color{violet}("catalyst.")`