Pollution is the effect of undesirable changes in our surroundings that have harmful effects on plants, animals and human beings. During the last few decades we have contaminated our air, water and land on which life itself depends with a variety of waste products.
Noise is undesirable and unwanted sound. The differences between sound and noise is often subjective and a matter of personal opinion. Sound is measured in a unit called the ‘Decibel (dB)’. The permitted noise level is 125 decibels, as per the Environment (Protection) (second amendment) Rules, 1999.
- Outdoor Noise Pollution: Noise emanating from factories, vehicles, playing of loudspeakers during various festivals, etc
- Indoor Noise Pollution: Loudly played radio or music systems, and other electronic gadgets, etc
- The most direct harmful effect of excessive noise is physical damage to the ear and the temporary or permanent hearing loss often called a temporary threshold shift (TTS). A sound level of 150 dB or more can physically rupture the human eardrum.
- Noise can also cause emotional or psychological effects such as irritability, anxiety and stress. Lack of concentration and mental fatigue are significant health effects of noise.
There are four fundamental ways in which noise can be controlled. In general, the best control method is to reduce noise levels at the source.
- Reduce noise at the source
- Muffling vehicles and machinery to reduce the noise
- In industries using rigid sealed enclosures around machinery lined with acoustic absorbing material
- Isolating machines and their enclosures from the floor
- Regular and thorough maintenance of operating machinery, etc
- Establishing lower speed limits for highways that pass through residential areas, limiting traffic volume and providing alternative routes for truck traffic are effective noise control measures.
- Block the path of noise
- The path of traffic noise can also be blocked by construction of vertical barriers alongside the highway.
- Planting of trees around houses can also act as effective noise barriers.
- In industries different types of absorptive material can be used
- Highly absorptive interior finish material for walls, ceilings and floors can decrease indoor noise levels significantly.
- Increase the path length:
- Noise levels at construction sites can be controlled using proper construction planning and scheduling techniques. Locating noisy air compressors and other equipment away from the site boundary along with creation of temporary barriers to physically block the noise
- Protect the recipient
- Use of earplugs and earmuffs can protect individuals effectively from excessive noise levels.
The discharge of warm water into a river is usually called a thermal pollution.
It occurs when an industry (e.g. power plants) removes water from a source, uses the water for cooling purposes and then returns the heated water to its source.
Power plants heat water to convert it into steam, to drive the turbines that generate electricity. For efficient functioning of the steam turbines, the steam is condensed into water after it leaves the turbines. This condensation is done by taking water from a water body to absorb the heat. This heated water, which is at least 15 degrees higher than the normal is discharged back into the water body.
The warmer temperature decreases the solubility of oxygen and increases the metabolism of fish. This changes the ecological balance of the river.
Tropical marine animals are generally unable to withstand a temperature increase of 2 to 3 degrees and most sponges, mollusks and crustaceans are eliminated at temperatures above 37 degrees. This results in a change in the diversity of fauna as only those species that can live in warmer water survive.
Rising temperature of sea water causes coral polyps expel algae that live inside their tissues called ‘Coral Bleaching’.
Thermal pollution can be controlled by passing the heated water through a cooling tower after it leaves the condenser. The heat is dissipated into the air and the water can then be discharged into the river or pumped back to the plant for reuse as cooling water.
Construction of a large shallow cooling pond is used to dissipate heat from the hot water pumped into one end of the pond and cooler water is removed from the other end.
Any undesirable effect caused to the environment due to radioactive substances or radiations is called nuclear pollution.
- Accidental leakage from nuclear facilities (i.e. power plants) (like Three Mile Island and Chernobyl incidents)
- Nuclear explosions that are performed while conducting nuclear tests
- Nuclear weapons as weapons of mass destructions (WMD) (i.e. Hiroshima and Nagasaki explosions)
- Radiation from radioactive waste
- Cosmic rays from outer space have intense radiation\
- Medical equipment using radioactive isotopes (like in cancer)
- Genetic Mutations: Nuclear pollution is the most dangerous for the environment since the wastes maintain their radioactive properties for thousands of years. Radiation, that is given off by nuclear waste is extremely damaging to organisms, because it causes mutations at a very high rate.
- Diseases: At high doses, nuclear radiation is lethal but at lower doses, it creates various disorders, the most frequent of all being cancer.
- Harmful to ecosystem: Radioactive particles in the atmosphere settle (called Fallout) on the leaves of plants and water bodies and thereby enter into the ecosystem.
- Reduced crop productivity: Radioactive substances in the soil react together with the various nutrients leading to destruction of those nutrients, thus rendering the soil infertile and highly toxic.
- Proper storage of nuclear fuel
- Proper disposal of radioactive wastes
- Better nuclear reactor and fuel in producing nuclear energy
- Banning nuclear tests and nuclear weapons
- Careful handling of equipment dealing with radioactive isotopes
More Topics from Paper- IV: Applied Science