Air pollution

Air pollution is defined as the presence of any liquid, gaseous or solid substance which includes noise and radio active radiation in the atmosphere in such concentration that may be directly and indirectly injurious to human or other living organisms, plant, property or interferes with the normal environmental process.
According to who Air pollution kills an estimated seven million people worldwide every year.

  • The main pollutants of air pollution are particulate matter, PAHs, lead, ground-level ozone, heavy metals, Sulphurdioxide, benzene, carbon monoxide and nitrogen dioxide.
  • Along with harming human health, air pollution can cause a variety of environmental
    effects: Acid rain, EutrophicationHaze, Effects on wildlife, Ozone depletion, Crop and forest damage, Global climate change
  • Air pollution is the main reason of ill health and death.
  • Combustion from Industry, Transportation Emissions, Agriculture Side-Effects, Agriculture Side-Effects, Home Cooking, Volcano Eruptions, Forest Fires, Tobacco Smoke, Metal Smelting, Aerosols and CFCs etc. are the main causes of air pollution.

  • Indoor air pollution is restricted to buildings only. It is the amount of chemical,biological and physical contaminants in the air inside a building. Building materials, central heating and cooking devices, painting colours, stoves, gas heater, and tobacco smoke, etc. are the examples of indoor air pollution.

Outdoor Air Pollution

The common sources of outdoor air pollution are emissions caused by combustion processes from motor vehicles, Burning Garbage, solid fuel burning and industry.
Release of several air pollutants into the atmosphere which causes severe threat to living organisms or upsetting the functioning of environment is called outdoor air pollution.

Contributors of Pollutants

  • Diesel exhaust is a contributor to pollution.
  • Volcanic eruptions release more sulphur fumes than all power plants and all industries in the world.
  • Trees emit hydrocarbons called terpenes causing bluish haze.
  • There are natural pollutants of air like animal decay.
Sr. No.PollutantOriginEffect
1Arsenic (AS)Coal, oil furnaces, glass factoriesLung and sking cancer
2Benzene (C6H6Refineries, motor vehiclesLeukemia
3Cadmium (Cd)Smelters, coals, oil furnacesDamage to lung, kidney, bones
4Chlorine (Cl)ChemicaL Industries, volcanic activitiesCauses irritation
5Carbon monoxide (CO)Motor vehicles, smelters, coal steel plants Starves body of oxygen, damages heart
6 Fluoride (F) Smelters, Steel Plants Mottles teeth in children
7 Hydrocarbons Unburnt gasolene fumes, motor vehicles Combines with nitrogen oxides in sunlight to form smog, causes irritation in eyes and nose
8 Formaldehyde (HCHO) Chemical plants Allergenic, carcinogenic, headaches, burning sensation in the throat, and can aggravate asthma symptoms
9 HCL (Hydrogen chloride) Incinerators Irritates eyes and lungs
10 Hydrogen fluoride (HF) Fertilizer plants Smelters Irritates skin, eyes, mucous membrane
11 Mercury (Hg) Coal, smelters oil furnances Tremors, nerve troubles
12 Nitric acid (HNO3) Formed from NO2 causes acid rain Respiratory disease
13 Nitrous acid (HNO3) Formed from NO2 and water vapour  Respiratory disease
14 Hydrogen sulphide (H2S) Refineries, Pulp mills Nausea, irritates eyes
15 Sulphuric acid (H2SO4) Formed from SO2 in sunlight with Respiratory disease hydroxyl ions
16 Manganese (Mn) Steel and sulphur dioxide power plants Parkinson’s diseases
17 Nickel (Ni) Smelters, coal, oil Lung Cancer furnaces
18 Nitric Oxide (NO) Motor Vehicles, coal, oil furnaces Oxidizes to NO2
19 Nitrogen dioxide (NO2) Formed in Sunlight from NO Bronchitis Loss of resistance to influenza forms Ozone
20 Ozone (O3) Ground Level ozone formed from nitrogen oxides (NOx) and volatile organic compounds (VOCs) Asthma, irritates eyes sunlight from nitrogen oxides and hydrocarbons
21 Lead (Pb) Motor vehicles, high smelters Brain damage
22 Silicon Tetra fluoride (Sif4) Chemical plants Lung diseases
23 Sulphur dioxide (SO2) Smelters Coal, Oil furnaces Irritates eyes, breathing problems

Auto Fuel policy

The National Auto Fuel Policy (2003) mandated that all new four-wheeled vehicles in 11 cities meet Bharat Stage III emission norms for conventional air pollutants (similar to Euro III emission norms) and comply with Euro IV standards by 2010.

The vehicular emission norms were introduced in India in year 2000 and in the same year Bharat Stage norms were adapted. The Bharat stage II , equivalent to euro II norms, was made applicable in 11- cities, i.e. Agra, Ahmadabad, Bengaluru, Chennai, Delhi, Hyderabad, Kanpur, Kolkata, Mumbai, Pune and Surat. It had to be applicable to all automobiles throughout the country from April 1st 2005.

From 1st April 2005, all automobiles had to meet Euro III emission specifications in the above 11- cities.

By 1st April 2010, they had to meet Euro IV  norms. The rest of the country, by 2010, had to meet the rest of the country, by 2010, had to meet Euro III  emission norms for automobiles and the fuel. According to the norms of Euro III The sulphur was to be controlled at 150 ppm (parts per million) in petrol, and 350 ppm in diesel. The aromatic hydrocarbon were to be regulated at 42% of the fuel. The goal was to reduce sulphur to 50 ppm and hydrocarbon to 35% of the fuel.

According to the corresponding fuel the vehicular engines were also needed to be upgraded./Bharat Stage- IV (BS-IV) in certain States and Union Territories is to be introduced on 1st April, 2016, and in the rest of country on 1st April, 2017. ILn March 2017, supreme court of India banned the registration of BS-III vehicles in New Delhi.

BS-V emission norms for vehicles across the entire country will be implemented from 2019. BS-IV for four wheelers will be enforced in India from year 2023.

Prevention of air pollution

Air pollution can be reduced with the help of

  • Planting more trees
  • Using smokeless sources of energy like smokeless stoves, biogas, solar and wind energy.
  • Carpool, use public transportation, bike, or walk whenever possible.
  • Keep car, boat, and other engines properly tuned.
  • using devices for filtering smoke in chimneys of factories and power houses.
  • Locating industries away from residential areas.
  • Using CNG
  • Avoid burning leaves, trash, and other materials.
  • Strictly checking pollution levels in automobiles exhaust emission by using catalytic converter.

Air Quality Index

National Air Quality Index was launched by the Prime Minister in April, 2015 starting with 14 cities to dis-seminate air quality information. The AQI has six categories of air quality, viz Good, Satisfactory, Moderately Polluted, Poor, Very Poor and Severe with distinct colour scheme. Each of these categories is associated with likely health impacts. AQI considers eight pollutants (PM10, PM 2.5, NO2, CO, O3, NG3, NG3 and Pb) for which (up to 24- hourly averaging period) National Ambient Air Quality Standards are prescribed.

AQI Category, Pollutants and Health Breakpoints
AQI Category (Range)PM10 24-hrPM2.5 24-hrNO2 24-hrO3 24-hrCO 8-hr (mg/m3)SO2 24-hrNH3 24-hrPb 24-hr
Satisfactory (51- 100)51-10031-5041-8051-1001.1-2.041-80201-4000.5-1.0
Moderately polluted (101-200)101-25061-9081-180101-1682.1-1081-380401-8001.1-2.0
Very poor (301-400)351-430121-250281-400209-748*17-34801-16001200-18003.1-3.5
Severe (401-500)430+250+400+748+*34+1600+1800+3.5+