Environment Pollution – Air Pollutants

Environmental Pollution

Pollution is the introduction of contaminants into the natural environment that cause adverse change. Pollution can take the form of chemical substances or energy, such as noise, heat or light. Pollutants, the components of pollution, can be either foreign substances/energies or naturally occurring contaminants.

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

Major Air Pollutants
CO	By incomplete combustion of carbon-based fuels, Automobile exhaust, Cigarette smoke Combines with haemoglobin 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 logarithmic 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, CCl_4,CH₃CCl_3,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

Environment Pollution – Air Pollutants

Environment Pollution – Air Pollutants