Pollution – Water & Air

Water Pollutants

Sources – community waste water, Industrial waste, Agricultural chemicals waste, Thermal & nuclear pollution, Oil spills, Radioactive dump waste, Groundwater seepage etc.

  • Sudden rise in water temperature due to thermal pollution, which uses water as coolant & releases hot water to source, kills aquatic animals as they have a very narrow tolerance limit with respect to temperature
  • Polluted water reduces dissolved oxygen which leads to depletion of aquatic flora & fauna
  • Oil spills in water can be cleaned with the help of Bregolia byproduct of paper industry
  • Water hyacinth (an aquatic weed) can purify water by taking some toxic materials & a number of heavy metals from water.

Water Pollutants

Biochemical oxygen demand

  • amount of dissolved oxygen needed by bacteria in decomposing the organic waste present in water
  • Actually a measurement of pollution by organic wastes expressed as milligram of oxygen / liter water

Higher value of BOD indicates low dissolved oxygen in water (BOD is only limited to biodegradable materials only)


Chemical oxygen demand

  • a measure of oxygen equivalent required for oxidation of total organic matter i.e. degradable & non degradable, present in water.


Diseases by Water Pollution


  • A crippling deformity caused by methyl mercury poisoning mainly by industrial waste water
  • first described in the inhabitants of Minamata Bay, Japan and resulted from their eating fish contaminated with mercury industrial waste


itai itai

  • Also known as ouch ouch disease (pain in bones & joints) caused by water contamination by cadmium


Blue Baby Syndrome

  • Excess nitrates in drinking water reacts with hemoglobin to form nonfunctional methaemoglobin which impairs oxygen transport


Skeletal Fluorosis

  • Excess of fluorides in drinking water can cause neuromuscular disorders, teeth deformity, and hardening of bones, painful joints & outward bending of legs from knees – Knock knee syndrome


Black foot disease

  • Caused by leaching of arsenic from soil & rocks to ground water used for drinking purposes


Water contaminated with lead

  • Cause anemia, loss of muscle power & bluish lines around the gums


Iodine 131

  • Produced by nuclear tests, passed to vegetation & then appears in milk of the cattle that consume the contaminated vegetation & is passed to humans.
  • causes serious damage to thyroid glands especially among children


Sick building syndrome (SBS)

  • a situations in which building occupants experience acute health and comfort effects that appear to be linked to time spent in a building, but no specific illness or cause can be identified
  • causes are frequently pinned down to flaws in the heating, ventilation & air conditioning (HVAC) systems


Pollution in Leather Industry

  • Leather industry in India has become 0 discharge industry as ~80% of the effluents are treated and recycled back into use and remaining 20% are solidified and their salts used for other purposes.
  • As a result, Indian leather industry is REACH compliant (EU norms) and exported $4.5 bio in 2011-12 and the target is $14 bio by 2015-16 (growth rate of 20% p.a.)

Air 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

  • 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
  • Major greenhouse gas formed by respiration, burning of fuels, decomposition of lime, volcanic eruption
  • 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)
  • 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
  • Formed when NOx particle from vehicle exhaust & volatile Hydrocarbons interact with each other in presence of sunlight
  • SPMs in air, when breathed in causes lung damage & respiratory problems
  • 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
  • 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
  • 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
  • CO2, CH4, CFC, N2O, SF6, HFCs, PFCs, CCl4, CH3CCl3,  Water Vapour, O3
  • Mainly from carpets, particle boards & insulation foam  Causes irritation & allergies
  • 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



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



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



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

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