Pollution

Air Pollution

Air pollution is the presence of solid, liquid and gas in the atmosphere at concentrations capable of harming humans, other organisms, properties or environment. Major pollutants can be classified as

• Primary Pollutants
  • These are emitted directly into the atmosphere
  • It includes
    • PM2.5
    • PM10
    • SO₂
    • NO_x
    • CO
    • VOCs
    • PB (lead)
    • NH₃
• Secondary Pollutants
  • These are formed through atmospheric chemical reaction
  • This include
    • Ground level ozone
    • Secondary nitrate
    • Secondary organic aerosols

Major Sources

Important Air Pollutions and their Properties

• Carbon Monoxide
  • It is produced from incomplete burning of carbon-based fuel including petrol, diesel and wood coal.
  • It is also produced from the natural combustion of synthetic products like paper, cigarette, etc.
  • It lower the amount of oxygen in our blood thus, it slows down our reflexes and make us confused and sleepy.
• Carbon dioxide
  • It is a most important greenhouse gas.
  • It is emitted from both combustion and non-combustion activities.
  • Combustion activity include fossil fuel burning, forest fire, industrial chimneys, etc.
  • Non-Combustion activity include respiration by animals and plants, deforestation, agricultural practices, production of some products like iron-steel, cement, etc.
• Lead
  • It is present in petrol, diesel, paint, hair dry and batteries.
  • It causes nervous system damage.
  • It affects children in particular and affect their digestive system and sometimes causes cancer.
• Ground level Ozone
  • It lower our resistance to cold and causes pneumonia.
  • It causes eye burn, eye itching and watery eye, chest pain and respiratory issues.
• NO_x
  • It is third most abundant well mixed greenhouse gas after CO₂ and CH₄.
  • It is naturally present as a part of nitrogen cycle.
  • It comes from biomass burning, industrial production of fertilizers, forest, stable burning, urine, etc.
  • It causes smog and acid rain.
• SPM (Suspended Particulate Matter)
  • It causes lung irritation, reduce RBC formation and respiratory diseases.
• Sulfer dioxide
  • It comes form fossil fuel burning, largest source is thermal power plant other sources are volcanic eruptions, smelting of metals.
  • It causes acid rain and lung diseases.
• Water Vapour
  • Important greenhouse gas however not include in Kyoto Protocol.
• Methane
  • It is second largest greenhouse gas after CO₂.
  • It comes from marshy land, wetland where anaerobic degradation of organic matter take place.
• Chlorofluorocarbons (CFCs)
  • These are manufactured molecules containing chlorine, fluorine and carbon.
  • Its sources are refrigeration, insolation, propellants, solvents or packaging material, etc.
  • It causes climate change and global warming.
• Smog
  • Smog is equal to smoke plus fog.
  • There are two types of smog
    • Classical Smog
      • It is called reducing smog or London Type of smog because it was first observed in 1950s in London.
      • It is also called sulfureous smog due to high presence of sulfer dioxide (comes from thermal power plant).
      • Thus classical smog is equal to SO_x + Particulate Matter + Black Carbon + Metallic dust + others.
      • It is formed in the winter morning and dissolves or reduces with sunrise.
    • Photochemical Smog
      • It is also called Los Angeles Smog or Oxidizing smog.
      • PCS = NO_x + PAN (Peroxyacetyl Nitrate) + PBN (Peroxybenzyl Nitrate) + VOCs + H₂O + Aldehyde + Ground level Ozone.
      • It is very common in urban areas during daytime.
• Fly Ash
  • Fly ash is produced whenever combustion of solid material take place.
  • It is one such residue which rises with gases into the atmosphere.
  • It is a very fine powder whose main component is aluminium, silicate, silicon dioxide and calcium dioxide.
  • When it falls on the agricultural fields it compromises their fertility.
  • When it falls on the tree leaves it blocks stomata and reduces photosynthesis. Thus is highly harmful to the ecosystem.
  • By using electrostatic precipitator and other particle filtration equipment fly ashes are captured e.g. in Maharashtra and it is used for making bricks or mixing with Portland Cement up to 35%.

Indoor Air Pollution

It refers to the physical, chemical and biological characteristics of air in indoor environment, within a home or and institution or commercial complex. As per ICMR's report indoor air pollution is 1000x times more harmful then outdoor air pollution. It is of two types.

• Rural Indoor Pollution
  • It comes from wood burning, charcoal, cow dung burning, pesticides like moth repellent, etc.
• Urban Indoor Pollution
  • It comes from refrigerators , detergents, perfumes, hair spray, furniture polish, air fresheners, wood preservatives.