Air Pollution

Air pollution occurs due to the presence of undesirable solid or gaseous particles in the air in quantities that are harmful to human health and the environment. It can be defined as the presence of foreign matter, either gaseous or particulate (or a combination of both), in the air that is detrimental to the health and welfare of living beings.

Primary vs. Secondary Pollutants

• Primary Pollutants: Emitted directly from identifiable sources and may be natural (e.g., volcanic eruptions, dust storms) or human-made (e.g., emissions from vehicles and industries). They include carbon oxides (CO and CO2), nitrogen oxides (NOx), sulfur oxides (SOx), volatile organic compounds (VOCs), and suspended particulate matter.
• Secondary Pollutants: Produced in the atmosphere through chemical reactions between primary pollutants and other atmospheric components. Examples include sulfuric acid, nitric acid, carbonic acid, and acid rain.

Types of Particulate Matter

Particulates can be:

1. Natural: Such as dust, pollen grains, spores, algae, fungi, bacteria, and viruses.
2. Anthropogenic: Produced by human activities such as cement dust, mineral dust, asbestos dust, smoke from fires, and fly ash.

Causes of Air Pollution

Air pollution originates from both natural and artificial sources:

1. Natural Pollution: Includes sources like oceanic aerosols, volcanic emissions, biogenic sources, wind-blown terrestrial dust, and lightning.
2. Artificial Pollution: Generated from human activities such as:
   • Fuel Burning: In industries and power plants.
   • Refuse Burning: Includes burning of waste materials.
   • Transportation: Emissions from vehicles.
   • Industrial Emissions: From chemical factories, metallurgical factories, etc.
3. Solvent Usage: Sources include spray painting and solvent extraction.

Major Sources of Air Pollution

1. Industrial Chimneys: Industries like petroleum refineries emit gaseous pollutants (e.g., SO2 and NO). Cement factories release dust, while chemical manufacturing industries emit acid vapors.
2. Thermal Power Stations: Coal-powered stations, such as those managed by the National Thermal Power Corporation (NTPC), emit pollutants like fly ash, SO2, and other gases.
3. Automobiles: A major source of air pollution, producing emissions from exhaust systems, fuel tanks, carburetors, and crankcases. These include unburnt hydrocarbons, CO, NO, and lead oxides.

Effects of Air Pollution

Effects on Human Health:

• • Carcinogenic Effects: Particulate matter accumulates in the lungs and causes lung cancer and respiratory issues.
  • Carbon Monoxide (CO): Even low concentrations can lead to headaches, drowsiness, coma, and even death. It reduces the oxygen-carrying capacity of blood.
  • Sulfur Dioxide (SO2): Irritates respiratory tissues.
  • Nitrogen Dioxide (NO2): Aggravates asthma and susceptibility to infections.
  • Volatile Organic Compounds: Such as benzene and formaldehyde, can cause mutations and cancer.

Effects on Plants:

• • Pollutants damage plant leaves, interfere with photosynthesis, and stunt growth.
  • Pollutants also reduce nutrient uptake, causing leaves to yellow, brown, or fall prematurely.

Effects on Materials: Air pollutants degrade the exterior paint of vehicles and buildings.

Effects on the Stratosphere: Ozone Layer Depletion: Ozone in the stratosphere protects Earth from harmful UV radiation. Certain pollutants deplete this ozone layer, leading to increased UV radiation at the Earth’s surface.

Consequences of Ozone Depletion:

1. • Human Health: Increased risk of skin cancer, cataracts, sunburns, and weakened immune systems.
   • Food Production: UV radiation reduces the ability of plants to photosynthesize, affecting their growth and nutrient content.
   • Climate Change: Increased UV radiation contributes to global warming and climate change.

Control Measures for Air Pollution

Two approaches:

Preventive Techniques:

• • Reducing the generation of pollutants through cleaner technologies and alternative materials.
  • Using unleaded petrol in vehicles.
  • Substituting raw materials that cause pollution with those that cause less harm.

Effective Control:

• • Pollution Removal Equipment: Devices such as scrubbers, filters, and electrostatic precipitators help remove pollutants from fuel gases.
  • Higher Smoke Stacks: Elevating pollution sources to reduce ground-level concentration.
  • Proper Industry Location: Industries should be placed in locations that minimize pollution’s impact, taking into account topography and wind direction.