< General Studies Home Page

Content

• Pollution and Pollutants
• Air Pollution
• CO2
• Suspended Particulate Matter (SPM)
• Carbon monooxide
• Ozone
• Nitrogen dioxide
• SO2
• Benzene
• Ammonia
• Smog
• Aerosol Pollution
• Fly Ash
• Indoor Air Pollution
• Pet Coke (Petroleum Coke) and Associated Issues
• Fuel Oil/ Heavy Oil/ Furnace Oil -> Issues Concerning Them
• Agri-Subsidy and Air Pollution
• WHO’s Air Quality Guidelines

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1. POLLUTION AND POLLUTANTS

• Pollution refers to introduction of harmful materials (pollutants) into environment.
• Many things which are useful to people produce pollution.
  • Vehicles, Electricity production, Fertilizers, Pesticides, Plastic etc.
• There are various types of pollution – Air Pollution, Water Pollution, Soil/Land pollution, plastic pollution, noise pollution, light pollution etc.
• There are various ways of classifying pollutants:
  1. Primary vs Secondary
     • Primary Pollutants: It is an air pollutant emitted directly from the source.
       • Examples of primary pollutants: (Particulates, CO, NO2, SO2 )
     • Secondary Pollutant: It is not directly emitted from the source as such, but forms when other pollutants (primary pollutants) react in the atmosphere.
       • Examples of secondary Pollutants: (Ozone, NO2, Acid Rain, Haze (Organic Aerosol))
  2. Quantitative Pollutants vs Qualitative Pollutants
     • Quantitative Pollutant: These substances are naturally present in environment. They become problematic only when their quantity increase.
     • Qualitative Pollutant: These are not naturally present in environment and are introduced in environment by human activities. E.g., Fungicide, herbicide etc.
  3. Persistent Pollutant vs Non-Persistent Pollutant
     • Persistent Pollutants are those pollutants which remain consistent in the environment for a long period of time without any change in its original form. (For e.g., nuclear wastes, pesticides, plastics etc.)
     • Non-Persistent Pollutants are the opposite of persistent pollutants and breakdown in the simple form.
  4. Biodegradable vs non-Biodegradable
     • Biodegradable pollutants are the pollutants which can be decomposed by micro- organisms.
     • Non-biodegradable pollutants are those which are not decomposed by microbial action (e.g., plastics, glass, DDT, salts of heavy metals etc.)
  5. Natural vs Anthropogenic

3. AIR POLLUTION

• Air pollution is contamination of the indoor or outdoor environment by any chemical, physical or biological agent that modifies the natural characteristics of the atmosphere: WHO.
• Sources of Air pollution:
  • Vehicular emissions, industrial fuel burning, energy production, forest fires, household combustion etc.
• Pollutants of major public health concern include PM, CO, Ozone, NO2, SO2, Smog, Hydrocarbon, CFCs

 1) CO2                                        

• It is a greenhouse gas which results into global warming.

 2) SUSPENDED PARTICULATE MATTER (SPM)

A) PM2.5

• 5 is defined as ambient airborne particulates (including dust, soot, dirt, smoke, and liquid droplets) that measure upto 2.5 microns in size. These particles include a range of chemical makeups and come from a range of source.
• Main sources include fossil fuel powered vehicles, power generation, Industries, Agriculture and biomass burning
  • Chemical reaction between gases can also be a source of PM2.5 This include reactions between: SO2, NO2, Ammonia, Black carbon, Mineral dust, water, volatile organic carbon.
• Among criteria pollutants commonly measured in real time, fine particulate matter (PM2.5) is currently understood to be the most harmful to human health. Due to very small size, they can remain suspended in air for long periods and the microscopic size allows these particles to be absorbed deep into the bloodstream upon inhalation.
• Exposure to 5 have been linked to negative health effects like cardiovascular diseases, respiratory illness, premature mortality, low birth weight, and stroke.
• 5 can also cause negative environmental impact: Damage to materials and buildings; Acid Deposition; increase ozone levels.

B) PM10

• PM10 are suspended coarse particles, either solid or liquid, with a diameter of 10 micrometers or less. For comparison, a human hair is, on average, 50 to 70 micrometers in diameter. They are also sometimes referred to as floating dust or aerosols.
• Difference between PM2.5 and PM10
  • Size: PM2.5 is very fine, and PM 10 is larger and coarser.
  • Less Harmful: PM10 is less likely to cross from lungs to the bloodstream. Though they can penetrate deep into lungs.
• Various sources:
  • Smoke, Dust, and dirt from unsealed road, construction, landfill and agriculture
  • Pollen
  • Mold
  • Smoke
  • Industrial sources
  • Fossil fuel burning
  • Sea Salt
• Health Impact:
  • Short term – Difficulty breathing; coughing; eye, nose and throat irritation; Chest tightness and pain; Fatigue; General respiratory discomfort.
  • Long term impact: Heart failure, asthma, heart failure, cancer, adverse birth outcomes etc.
• Environmental Impact: Can corrode organic and inorganic material from vegetation to buildings. Painted surfaces, stone, fabrics, metal, and wood can become damaged and discolored.

 3) CARBON MONOOXIDE

• CO is an odorless, colorless, and tasteless gas produced by the incomplete combustion of carbon in fossil fuels such as wood, propane, charcoal, oil, coal or other fuel.
• Carbon monoxide Poisoning: It occurs when carbon monoxide builds up in your bloodstream. When too much CO is in the air you’re breathing, your body replaces the oxygen in your RBCs with carbon monoxide. This prevents oxygen from reaching your tissues and organs.
  • Science behind this:
    • Hemoglobin binds carbon monoxide (CO) 200 to 300 times more with oxygen, resulting in the formation of carboxyhemoglobin and preventing the binding of oxygen to hemoglobin due to competition of the same binding sites.
  • Signs and symptoms of CO Poisoning: Dull headache, weakness, dizziness, nausea or vomiting, shortness of breath, confusion, blurred vision, loss of consciousness etc.
  • It can particularly be dangerous for people who are sleeping or intoxicated. People may have a irreversible brain damage or even die before they realize the problem.

 4) OZONE

• Ozone (O3)
  • Ozone is a gas composed of three atoms of oxygen (O3).
    • Key Properties: It is a bluish gas. It is also a major oxidant.
  • It occurs in both earth’s upper atmosphere and at ground level.
  • Ozone can be “good” or “bad” for health and the environment depending on where it’s found in atmosphere.
• What is Ground Level Ozone Pollution?
  • Ozone pollution is a secondary pollution and is not emitted by source directly. It is created by chemical reactions between oxides of Nitrogen (NOx) and Volatile Organic Compounds that are emitted from combustion sources like vehicles, industry, power plants etc. in the presence of sunlight and heat.
  • It is most likely to reach unhealthy levels on hot sunny days in urban environment. It may also reach high level during colder winter months because of high pollution and sunlight.
  • Since it can also be transported for long distances by wind, it may also impact rural areas.
• Unprecedented Ozone Levels have made Delhi Air More Toxic: CSE analysis (June 2022)
• Why increasing in Delhi
  • High level of pollution, with high sunshine and high ambient temperatures.
• Negative Impact of Ozone Pollution
  • Health Impacts -> Breathing problems, chest pain, cough, throat irrigation; Further people with certain genetic conditions, and people who have lower intake of Vitamin C and Vitamin E are at greater risk of Ozone exposure.
  • Environmental Impact –> impact sensitive vegetation during growing season
• Monitoring of Ozone
  • NAAQS (National Ambient Air Quality Standards) by CPCB measures Ozone
  • AQI and SAFAR measurements also has listed ozone as a pollutant which is regularly measured.

 5) NITROGEN DIOXIDE 

• Details
  • Physical features: It is a deep red-orange gas and when released into the air, it is seen as a reddish-brown haze. It has a pungent and acrid odour.
  • NO2 is a major contributor in the formation of Smog and a precursor to many harmful secondary pollutants, including ozone and particulate matter. It is highly reactive with other chemicals and is strong oxidizing agent.
  • Sources of NO2
    • Natural Sources:
      • Lightning Strikes
      • Volcanoes
      • Oceans
      • Biological decay
    • Manmade sources:
      • Combustion creates oxides of nitrogen, a major portion of which is nitrogen di oxide. When vehicles emit oxides of nitrogen, 90-95% of the emissions are nitric oxide (NO). However, nitric oxide quickly oxidizes in outdoor air when reacting to oxygen, ozone, and volatile organic carbons (VOCs) to form nitrogen dioxide.
  • It is both a primary and secondary pollutant.
    • As primary pollutant, NO2 is emitted in limited amounts through
    • It is also a secondary pollutant as it can be formed through oxidation. Nitrogen dioxide further oxidizes into Nitric Acid (HNO3), which can enter the environment through the ground as droplets or nitrate containing particles.

 6) SO2

• Basics
  • SO2 is a colorless gas which has a nasty, sharp smell. It reacts with other substances to form harmful compounds, such as sulfuric acid, sulfurous acid, and sulfate particles.
• Main Sources – Burning of Fossil fuels and ships, locomotives using furnace oil/ heavy oil; Other small sources are – industrial processes like extracting metal from ore; nature sources such as volcanoes.
• Why Sulphur dioxide pollution is problematic?
  • Health Issues: Respiratory diseases; contribute to PM pollution.
  • Environmental Issues ->
    • Harm trees and plants -> Damaging foliage and decrease growth of trees and
    • ACID Rain -> harms sensitive ecosystem
  • Damage Cultural Heritage
    • Deposition of sulfur particles may cause discoloration and damage of monuments, statues etc.
    • The fine particles may reduce visibility (Haze)
• India has emerged as the largest SO2 emitter in the world: NASA data.
  • India has highest number (more than 15%) of all anthropogenic SO2 hotspots in the world detected by the Ozone Monitoring Instrument (OMI) satellite. These include Singaruli, Nevyeli & Chennai, Talcher & Jharsuguda, Korba, Kutch etc.
• Key reasons for High Sulphur pollution in India
  • Nearly all the SO2 emission in India comes from coal burning power plants which are the major source of energy for India.
  • The vast majority of power plants in India lack flue-gas desulfurization technology to reduce their air pollution.
    • Note: Flue Gas Desulfurization (FGD) is a set of technologies used to remove SO2 from exhaust gas of fossil fuel based power plants.

7) BENZENE 

• Details
  • Benzene (C6H6) is an aromatic, organic compound with a single six-member unsaturated carbon ring. It is clear, colorless, volatile, highly inflammable liquid with a characteristic order and a density of 874/m3.
  • Benzene in air mostly occurs in vapor phase, with residence times varying between 1 day to two weeks, depending on the environment, the climate and the concentration of other pollutants.
  • It is an air pollutant emitted from gasoline stations, motor vehicle exhausts and fuel evaporation, the burning of coal and oil, and various other sources. Urban areas generally have higher ambient air concentration of benzene than other areas.
  • Indoor sources of benzene pollution are material used in construction, remodeling, and decorating. Benzene is also present in particle board, furniture, plywood, fiberglass, flooring adhesives, paints, wood paneling, paint removers etc. Therefore, new buildings or recently decorated indoor environments have been associated with high concentration of benzene from materials and furnitures. Use of fuel for space heating like coal, wood, gas, Kerosene, LPG etc. also produce benzene.
• Negative Health Impacts of Benzene
  • Cancer, damage to immune system, neurological, reproductive or developmental issues.
• In addition of being an air pollutant, it may also pollute water.
• Key recommendations
  • Installation of vapor recovery systems at the fueling stations
  • Retrofitting of diesel vehicles with particulate filters to improve air quality.
  • Stringent action against industrial units that don’t comply with emission norms.
  • Retrofitting of emission control devices of generators and replacing diesel generators with gas- based ones.
  • Promoting battery operated vehicles and banning old diesel vehicles in a phased manner, greening of open areas, and creation of green buffers along traffic corridors.

 8) AMMONIA 

• About Ammonia
  • Ammonia is a colorless gas with characteristics pungent odor.
  • Natural sources include decaying organic matter and animal waste.
  • Manmade sources include fertilizer manufacturing, waste disposal sites, industrial processes etc.
  • It doesn’t last long in environment and thus doesn’t bio-accumulate.
• Applications
  • 80-90% of ammonia all over the world is used for making fertilizer (ammonium nitrate is an important nitrogen fertilizer)
  • It is a precursor of various nitrogenous compounds. Virtually, all synthetic nitrogen compounds are derived from ammonia.
  • It is also used in making household cleaners, plastics, dyes, pharmaceuticals etc.
  • It is an anti-septic and is used in food preservation industry.
  • Scientists are also experimenting with using ammonia as a storage of renewable energy. (Nitrogen gas and water use energy to convert into Ammonia). Later Ammonia can be used a fuel in the fuel cell.
• Ammonia Pollution
  • Majority of airborne ammonia comes from fertilizers.
  • Ammonia can also contribute to formation of PM2.5 (ammonia combines with VOC, NOx, SO2 etc. to form PM2.5)
• Health Impacts:
  • At higher concentration ammonia is toxic, caustic, and hazardous. Exposures at high levels of ammonia can be irritating to a person’s skin, eyes, throat, lungs, and cause coughing and burns.
  • Long term health concerns associated with Ammonia exposure include – severe cardiovascular and respiratory effects, decreased lung function, asthma aggravation, premature death etc.
• Environmental Impacts -> Eutrophication, Soil Acidification; biodiversity loss -> promote species which prefer nutrient fueled growth to outcompete other species.
• Indo-Gangetic Plain Global Hotspot of atmospheric Ammonia: Study by IIT KGP (Dec 2020)
  • The Indo-Gangetic Plain is a global hotspot of atmospheric ammonia.
    • Reason: Intense agri activity and a lot of fertilizer use and production
  • Atmospheric Ammonia has a positive correlation with Fertilizer use, hot weather (high temperature supports volatilization) and fires.
  • It has a negative correlation with total precipitation as wet deposits helps in the removal of ammonia.
• Water Pollution
  • An ammonia concentration of upto 5 ppm (BIS) is maximum limit for drinking water. But, if the ammonia concentration is more than 1 ppm, it would negatively impact our health in long run. Similarly, ammonia concentration of more than 1 ppm in water bodies is dangerous for fish population.
  • High Ammonia Concentration in Yamuna River is regularly disrupting water supply in
    • For g., in July 2020, the ammonia concentration in Yamuna River reached 3 ppm. This led to reduction of water supply from Yamuna for Delhi, as Delhi Jal Board doesn’t have technology to treat this high concentration of water.
  • Why ammonia pollution is so high?
    • Industrial units of Sonipat and other drains joining the river along the way may be contributing to this.
• Way Forward – Precision agriculture; Regulation of discharge; Reducing Nitrogen feed to animals; Improving water treatment technology; maintaining ecological flow of water.

9) SMOG

• Smog
  • Smog is a kind of air pollution, originally named for the mixture of smoke and fog in the air.
    • Classical smog results from the large amount of coal burning in the area and is caused by mixture of Sulphur dioxide and smoke.
    • Today, most of the smog that we see is Photochemical Smog (or ground level Ozone). It is produced when Nitrogen oxides in presence of sunlight react with Volatile Organic Compounds (VOCs) in the atmosphere.
      • Nitrogen oxides come from car exhaust, coal power plants, and factory emissions.
      • VOCs are released from petrol, paints, and many cleaning
      • When sunlight hits these chemicals, they form airborne particles and ground- level Ozone or Smog.
• Harmful impacts of SMOG
  • Health Impacts: Ground level ozone, SO2, NO2, CO are especially harmful for senior citizens, children, and people with heart and lung conditions such as bronchitis and Asthama.
  • By decreasing visibility, it slows down traffic and increases the chance of
  • Smog also negatively affects the aesthetics of the city by making sky brown and gray.
• Supreme Court verdict:
  • The Supreme Court in Nov 2019 asked the CPCB and the Delhi government to come up with a road map on installing smog towers in the NCR to combat air pollution. In Jan 2020, the SC directed that the two towers should be installed by April as a pilot project.
• Components of Delhi’s first Smog tower by Government of Delhi:

• The tower uses a ‘down draft air cleaning system‘ developed by University of Minnesota.
  • Polluted air is sucked in at a height of 24 meters, and filtered air is released at the bottom of the tower, at a height of about 10 meters from the ground.
  • When the fan at the bottom layer operates, the negative pressure created sucks in the air from the top. The ‘macro layer’ in the filter traps particles of 10 microns and larger, while the ‘micro layer’ filters smaller particles of around 0.3 microns.
  • This method is different from the ‘Updraft system‘ – in which air is sucked in from the ground and is propelled upwards by heating and Filter air is released at the top of the tower.
• Expected Impacts
  • Computational fluid dynamics modelling by IIT Bombay suggest that towers could have an impact on air quality of upto 1 KM.
• Criticism
  • Experts say that there isn’t enough evidence to show that Smog towers work.

 10) AEROSOL POLLUTION

• What is aerosol?
  • An aerosol is a mixture of tiny particles suspended in a gas, typically air. This particle can be solid, liquid, or a combination of both. These particles can range in size from a few nanometers to several tens of micrometers and can be produced naturally or by human activities.
  • Examples of natural aerosols include dust, pollen, sea salt, and volcanic ash.
  • Examples of Human made aerosols include smoke, soot, exhaust fumes from vehicles, and particles generated by industrial processes like mining and manufacturing. They include PM2.5 and PM10.
• Impacts that aerosols can have:
  • On Human Health: they may cause respiratory problems and exacerbating heart disease.
  • On Environment: They can contribute to climate change by altering the balance of radiation in the atmosphere and affecting cloud formation.
• Aerosol Optical Depth (AOD):
  • It is a measure of how much atmospheric aerosols, such as smoke, dust, and pollution, are scattering and absorbing sunlight.
    • It is typically measured using specialized instruments that detect the amount of light that is scattered or absorbed by aerosols in the atmosphere.
    • It is the quantitative estimate of the aerosol present in the atmosphere, and it can be proxy measurement of PM2.5.
  • The value of AOD range from 0 and 1. 0 indicating crystal-clear sky with maximum visibility whereas a value of 1 indicates very hazy conditions.
  • AOD value less than 0.3 falls under green zone (safe), 0.3-0.4 is the blue zone (less vulnerable), 0.4-0.5 is orange zone (vulnerable) while over 0.5 is the red zone (highly vulnerable)
• Aerosol Pollution in West Bengal and Bihar (Nov 2022)
  • A study by Bose Institute in Kolkata as revealed that aerosol pollution in WB is anticipated to rise by 8% and continue to remain in the “highly vulnerable” red zone for aerosol pollution. This is the second highest forecasted aerosol pollution level in the country after Bihar.
  • India’s regional weather patterns and topography makes the country highly vulnerable to aerosol pollution.
• Why?
  • West Bengal receives Indo-Gangetic Plain air pollution outflows and its local emissions have put WB in the highly vulnerable zone.

 11) FLY ASH

• Introduction
  • Fly ash is a coal combustion byproduct produced in coal based thermal power plants. It refers to ash that is driven out of coal fired boilers together with the flue gases.
  • In modern coal fired power plants, fly ash is captured by electrostatic precipitators or other particle filtration equipment before the flue gas reaches the chimney.
  • The composition of fly ash varies considerably, but all fly ash includes substantial amount of Silicon di oxide (SiO2), Aluminium oxide (Al2O3) and Calcium oxide(CaO), the main mineral compounds in coal-bearing rock strata.
  • Note: The ash that falls to the bottom of the boiler is called bottom ash.
• Key characteristics of fly ash
  • Harmful for human health: Fly ash contains toxic constituents like lead, cadmium, chromium, arsenic which can be very dangerous for human health. They contribute heavily to particulate matters in air and cause lung problems.
  • Bad for environment
    • Toxic content results in both soil pollution and water pollution (toxic leaching)
  • Affects large land area.
    • If fly ash is not captured at the power plant itself, it spreads easily through air and affects large land area.
  • It is a pozzolan, a substance containing aluminous and siliceous material that forms cement in the presence of water. Hence it can be used in construction process.
• Reducing Fly Ash pollution
  • Washing the coal at its place of origin is an important step which ultimately reduces the amount of ash being produced.
  • Increasing R&D, for enhancing the efficiency of power plants, would also help in reducing the ash content.
  • Capturing fly ash before it is released in air by Chimney using various types of precipitators.
• Where can the captured fly Ash be used?
  • Cement industry uses Fly Ash in the manufacturing of Portland Pozzolana Cement.
    • Recently, scientists at IIT-Hyderabad have found ways to turn fly ash into products like paints, textile coatings
  • It can also be used fly ash bricks/blocks/ and tiles manufacturing, road embankments construction etc.
  • Fly ash may also be utilized in agriculture as soil conditioners.
  • It is also used as a substitute of soil/sand for reclamation of low-lying areas.
  • In mining it can be used for backfilling of mines.
• Steps taken to promote the use of Fly Ash?
  1. Various notification for fly ash utilization since 1999
     • The 2016 notification calls for every agency engaged in construction activity within a radius of 300 km of coal-based thermal power plant to use ash-based products for
     • It also mandates the use of ash-based bricks or products in all government schemes and programs.
  2. Maharashtra is the first state to have a Fly Ash Utilization Policy. It is also looking to export fly ash to countries like Singapore and Dubai where it is in demand.
  3. GST rates on fly ash and its products have been reduced to 5%.
  4. Launching of ASHTrack Mobile App for better management of fly ash produced by thermal power plant in Feb 2018.
     • It will act as an interface between fly ash producers (thermal power plants) and potential ash users such as road contractors, cement plants etc and thus will help in increasing the utilization of fly ash being produced at coal based thermal power plants.
  5. Various awareness campaigns
     • Through workshops and other

 12) INDOOR AIR POLLUTION

• Indoor Air Pollution or Household Pollution is the air pollution whose source lies within the household. Various recent studies have found that indoor PM2.5 level in most Indian households is much higher than the outdoor PM2.5 concentration of the respective geographic area.
• Causes:
  • Use of the traditional biomass (Cow dung cake, firewood, coal etc.) for cooking is the leading cause of air pollution.
  • Burning fuels such as dung, wood, coal in inefficient open hearth produce a variety of health- damaging pollutants, including particulate matter, methane, CO, polyaromatic hydrocarbon and VOCs.
  • These pollutants may further accumulate in the indoor environment if the indoor air is not well ventilated.
  • Tobacco consumption
  • Building Materials (Deteriorating asbestos containing insulation, paints, varnishes, wood flooring, etc.)
  • Products for household cleaning and maintenance, personal care, or hobbies.
  • Broken CFLs, Tubelights etc.
  • Increased penetration of closed ventilation due to Air-conditioners etc. makes situation worst.
  • Outdoor sources such as Radon, Pesticides, outdoor air pollution.
• Health Impacts
  • Household air pollution is responsible for 3.2 million deaths per year in 2020.
  • Household air pollution leads to non-communicable diseases including stroke, ischaemic heart disease, chronic obstructive pulmonary disease (COPD) and lung cancer.
  • The most common effect of IAP is called sick building syndrome, in which people experience uncomfortable or acute health effects such as irritation of nose, eyes and throats, skin ailments, allergies and so on.
• Key steps being taken by government.
  • RAISE initiative.
  • Unnat Chulha Abhiyan – By Ministry of New and Renewable Energy for providing a clean cooking energy solution with a view to reduce consumption of fuel wood with higher efficiency and low emissions.
  • PM Ujjwala Yojna

A) RADON (Rn222)

• It is an odorless, invisible, radioactive gas, naturally released from rocks, soil, and water.
  • It is a noble gas and thus doesn’t react chemically with other substances.
• It is formed by decay of uranium and thorium in the earth’s crust.
• It can seep into buildings and accumulate to dangerous levels, especially in areas with poor ventilation.
• Harmful Impacts:
  • Carcinogen: It can cause lung cancer.
    • In USA, radon is the leading cause of lung cancer after
• The risk of developing lung cancer from radon exposure depends on the level of radon in air, the duration of exposure, and whether or not the person is smoker.
  • Note: For smokers the risk is higher as smoking can damage the lungs and make them more susceptible to the harmful effects of radon.
• Detection of Radon:
  • Since, radon is colorless, odorless gas, the only way to know if the building has higher levels of radon is to test for it.
    • The test is relatively easy and inexpensive, and it can be done by homeowners and professionals.
• Some Steps that can be taken are:
  • Sealing cracks in the foundation
  • Installing a ventilation system
  • Relocating to different house

 13) PET COKE (PETROLEUM COKE) AND ASSOCIATED ISSUES

• Introduction: What is Pet Coke
  • It is a type of coke derived from oil refining process. It is the final carbon-rich solid material from the bottom of the barrel after refining of heavy oils.
    • Coking Process: In petroleum coker units, residual oils from other distillation processes used in petroleum refining are treated at high temperature and pressure leaving petcock after driving off gases and volatiles and separating off remaining light and heavy oils.
  • Properties
    • Petcoke is 90% carbon and emits 5-10% more carbon dioxide (CO2) than coal on a per- unit-energy basis when it is burned.
      • As they have higher energy content, they emit between 30-80% more CO2 than coal per unit weight.
    • It also contains higher sulfur content which makes it burning more polluting.
    • It is cheaper and burns hotter than coal.
  • Used less in western countries.
    • It’s higher sulfur content makes it a less attractive fuel in US and thus power hungry India becomes an easy export destination.
  • Impact of use of petcock in India
    • India is the largest user of the Pet coke.
    • It is making a bad situation worse in India due to its higher CO2 and Sulfur emissions.
• Ban on Pet Coke Import as fuel (Aug 2018)
  • DGFT has banned import of Pet-Coke as fuel.
  • Import is allowed for only Cement, Lime Kiln, Calcium carbide and gasification industries, when used as feedstock or in the manufacturing process of actual condition.

 14) FUEL OIL/ HEAVY OIL/ FURNACE OIL -> ISSUES CONCERNING THE

• Introduction
  • Fuel oil/ Heavy Oil/ Furnace Oil is the heavier fraction obtained from petroleum distillation.
  • Note: Fractional Distillation
    • Crude oil is separated into fractions by fractional distillation. The fractions at the top have lower boiling points than the fractions at the bottom.
    • All the fractions are processed further in refining units.
    • Bunker Fuel is the fuel used aboard vessels (heavy ships). Generally the heaviest variety of oil i.e. fuel oil is used there. It is also known as marine fuel oil.
• Some features of heavy fuel oil:
  • Heavy fuel combustion products remain high in NOx, Sox, Particulate matter and CO2.
  • It has high viscosity when compared to Diesel, Kerosene and Petrol. To be used as fuel it’s viscosity should be less and therefore it needs to be kept at higher temperature. It is also mixed with lighter fuel (e.g. diesel) to reduce its viscosity.
• In case of oil spills heavy oil is more aggravating in nature because:
  1. Marine fuel is hazardous and very toxic to marine life.
  2. It evaporates at a slower pace when compared to other fuel (petrol, Kerosene, diesel etc) and thus remain in water for longer period impacting marine diversity more.
• Despite the above limitations the use continues because of the cheap price and large availability (as it keeps getting produced in oil refineries)

 15) AGRI-SUBSIDY AND AIR POLLUTION

• High MSP for Rice -> Rice grown in Haryana, Punjab -> Stubble burning.
• Power subsidy -> more use of water -> paddy cultivation -> stubble burning
• Fertilizer subsidy -> Overuse -> Indo-Gangetic plains emerging as atmospheric ammonia hotspots

 16) WHO’S AIR QUALITY GUIDELINES

• In Sep 2021, WHO revised the air quality This was the first major update to the standards in 15 years.
• Why was there a need of update?
  • New studies have found that even smaller quantity of pollutants was harmful for human beings.
  • Therefore, WHO has strengthened nearly all pollutant standards in comparison to the quality guidelines established in 2005 (published in 2006)
    • Expected Impact: If the target levels are implemented and achieved by governments, it would lead to saving of lakhs of lives.
• The new guidelines recommend air quality levels for 6 pollutants, where evidence has advanced the most on health effects from exposure.

Recommended 2021 AQG levels compared to 2005 air quality guidelines

Pollutant	Averaging Time	2005 AQGs	2021 AQGs
PM2.5, µg/m³	Annual	10	5
	24-hour^a	25	15
PM10, µg/m³	Annual	20	15
	24-hour^a	50	45
Ο3, µg/m³	Peak season^b	-	60
	8-hour^a	100	100
ΝΟ2, µg/m³	Annual	40	10
	24-hour^a	-	25
SO2, µg/m³	24-hour^a	20	40
CO, mg/m³	24-hour^a	-	4

• Expected impact of the new guidelines:
  • Spur greater global reactions in pollution emissions.
  • Contribute to fight against climate.
• Note: These guidelines are not legally binding on any But, countries and legislative bodies regularly refer to WHO guidelines when setting airborne pollutant control legal policy.
• Implications for India
  • As per the new WHO guidelines, almost the entire India, specially the Urban areas would now be considered polluted for entire year.