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Environment Pollution – Air Pollutants

Environmental Pollution

Primary Pollutants: Persist in the form in which they are added to the environment for ex. DDT, Plastic

Secondary Pollutants: Formed by interaction among primary pollutants viz. PAN by interaction of NOx & Hydrocarbons

Biodegradable Pollutants: Waste products which are degraded by microbial action for ex. Sewage

Non-Biodegradable Pollutants: Not decomposed by microbial action for ex. Plastic, Glass, DDT, Radioactive substances

Quantitative Pollutants: Occur in nature & become pollutant when their concentration reaches beyond a threshold level for ex. CO2, NOx

Qualitative Pollutants: Do not occur in nature & are man-made for ex. fungicides, herbicides, DDT

Air Pollutants

Major Air Pollutants

 CO
  • By incomplete combustion of carbon based fuels, Automobile exhaust, Cigarette smoke
  • Combines with hemoglobin to form carboxyhaemoglobin, which is highly stable & reduces oxygen carrying capacity of blood
  • Slow our reflexes & make us confused & sleepy
CO2
  • Major greenhouse gas formed by respiration, burning of fuels, decomposition of lime, volcanic eruption
 CFCs
  • Released mainly from air conditioning systems & refrigeration
  • Detrimental to Ozone layer present in the stratosphere as CFC + UV >> Cl (Chlorine radicals which causes breakdown of Ozone)
Lead
  • Present in petrol, diesel, lead batteries, paints, hair dye products etc. (Affects children in particular)
  • Damages nervous system & cause digestive problems & in some cases causes cancer
O3
  • Formed when NOx particle from vehicle exhaust & volatile Hydrocarbons interact with each other in presence of sunlight
SPM
  • SPMs in air, when breathed in causes lung damage & respiratory problems
SO2
  • Produced from burning coal (60 %), mainly in thermal power plants + Petroleum products + in production of paper & smelting of metals
  • Major contributor to smog causing lung diseases
CH4
  • Mainly CH4 burns in fossil fuels + produced by burning of vegetation / rotting
Acid Rain
  • Ph < 5.6 (Rain with oxides of sulphur & nitrogen (SO2 & NO2)) – HNO3 + H2SO4
NOx
  • NO3-   Acts as a fertilizer to the soil
  • Automobile exhaust produces NO2 which damages plant leaves & retard rate of photosynthesis +  also causes red haze & lung irritation
Classical Smog
  • Occurs in cool humid climate
  • Chemically reducing hence called reducing smog
  • Smoke + fog + SO2
Ph value is a logrithmic index for hydrogen ion concentration in an aqueous solution, & each increasing Ph value diminish acidic nature of the solution by 1/10th

 

Photochemical Smog 
  • Occurs in warm, dry & sunny climate
  • Result from the action of sunlight on unsaturated HC & NOx produced by factories & automobile
  • Chemically oxidising hence called oxidising smog
  • Ozone + Acrolein + Formaldehyde + Peroxyacetyl Nitrate (PAN) are produced which cause serious health problems, severe plant damage, cracking of rubber & corrosion
  • Catalytic Converter – Prevent release of NO & HC to environment
GHGs
  • CO2, CH4, CFC, N2O, SF6, HFCs, PFCs, CCl4, CH3CCl3,  Water Vapour, O3
Formaldehyde
  • Mainly from carpets, particle boards & insulation foam  Causes irritation & allergies
 Radon
  • A gas naturally emitted by soil
  • Due to poor ventilation it is confined inside house & causes lung cancer

 



Fly Ash

  • Residue produced whenever combustion of solid material takes place, which rises with the gases in atmosphere & causes respiratory problems
  • Contains Aluminium silicates, SiO2 & Calcium oxide (CaO) + Toxic metals like lead, arsenic, cobalt etc.

 

Advantages of Fly Ash

  • Cement can be replaced by fly ash up to 35 % hence reducing cost of construction
  • Fly ash bricks are lighter in weight & offer high strength & durability
  • A better fill material for road embankments & concrete roads
  • Can be used in reclamation of wasteland, can increase crop yield & enhances water holding capacity of land

 

Sources of Air Pollutant Emission:  Industry > Transportation > Agriculture



Diseases By Air Pollutants

Yokkaichi asthma (SO2)

  • Burning of petroleum and crude oil releases large quantities of sulfur oxides which causes severe smog
  • Results in severe cases of chronic obstructive pulmonary disease, chronic bronchitis, pulmonary emphysema, and bronchial asthma

 

Pneumoconiosis / Black Lung Disease

  • an occupational lung disease caused by inhalation of coal dust, often in mines

Asbestosis

  • a lung disease, which leads to long-term breathing complications, caused by exposure to asbestos (No cure)

 

Silicosis

  • a lung disease that is caused by inhaling tiny bits of silica mainly by the workers working in silica industries or sand blasting sites

 

Emphysema

  • Breaking down of lung tissues due to air pollution & cigarette smoke leading to difficulty in expanding & contracting of lungs
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