Air Pollution

Dr. Akmal Rahim, Dr. Ajmal Rahim &

Dr. Seemal Vehra Ejaz

AIR

• Air: The invisible mixture of colourless, odorless and tasteless gases that surrounds the earth.

Air pollution

• Air pollution occurs when the air contains gases, dust, fumes or odour in harmful amounts. That is, amounts which could be harmful to the health or comfort of humans and animals or which could cause damage to plants and materials.

• Air Pollution is excessive discharge of undesirable foreign substances into the atmosphere, thereby adversely affecting the quality of air and causing damage to humans, plants, animals and materials.

Atmosphere

The envelope of gases surrounding the earth or another planet.

Atmosphere

Air Movements in the Troposphere Play a Key Role in Earth’s Weather and Climate

• Troposphere – 75–80% of the earth’s air mass

– Closet to the earth's surface

– Chemical composition of air

– Rising and falling air currents: weather and climate

– Involved in chemical cycling

The Stratosphere Is Our Global Sunscreen

• Stratosphere

–Similar composition to the troposphere, with 2 exceptions

• Much less water

• O3, ozone layer, filters UV

Air Pollutants • Carbon dioxide … CO

• Carbon Monoxide…CO2

• Sulphur oxides..SOx

• Nitrogen oxides…..NOX

• Hydrogen sulphide…HS

• Chloroflourocarbons ..CFC

• Ozone.. O3

• Methane…CH4

• Water vapours

• Particulate matter ..PM

Some Pollutants in the Atmosphere Combine to Form Other Pollutants

• Primary pollutants

• Secondary pollutants

• Air quality improving in developed countries

• Much more needs to be done in developing countries

Sources of Air pollution • Anthropogenic ( Manmade) Sources Population growth Burning of fossil fuels Emission from vehicles Rapid industrialization Deforestation Landfills…release gases Agricultural activities Wars

• Natural Sources Volcano eruptions Dust Living organisms Pollens

Air pollution is the addition of gases, chemicals, and particle matter into the atmosphere. Air pollution primarily comes from burning fossil fuels such as natural gas, petroleum, and coal.

And from Industrialization

Air Pollution

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Sources: Population growth

• Rapid increase in population requires:

- More oxygen

- Extra food

- Extra land for agriculture..food

• Results in pressure and stress on natural resources…..alters ecosystem processes…and becomes a prime cause of all sorts of pollutions

Sources: Emission from Vehicles

• Automobile exhausts are responsible for more than 75% of total air pollution.

• Pollutants include:

• Carbon monoxide

• NO x

• SOx

• Hydrocarbons

• Lead …when leaded petrol is used

• Incomplete combustion of engines

Sources: Rapid Industrialization

• Various industries:

Chemical industries, paper mils cotton mills, petroleum refineries, mines, rubber industries..etc together contribute about 20% of air pollution

• The most common pollutants from industries:

• Carbon dioxide … CO

• Carbon Monoxide…CO2

• Sulphur oxides..SOx

• Nitrogen oxides…..NOX

• Hydrogen sulphide…HS

Sources: Deforestation

• Forests are considered SINKS of CO2

• Deforestation…Removal or Cutting forests releases CO2 especially if it is burnt.

• Denuded, bare land results in wind erosion…dust enters atmosphere

Air Pollution

The waste in landfills releases methane. Sulfur oxides, carbon monoxide and carbon dioxide, and methane all have a very negative effect on air quality. These pollutants can also contribute to the greenhouse effect.

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Sources: Agricultural Activities

• Biocides...eg. Pesticides, insecticides, herbicides, which are used in agricultural practices also cause air pollution as these poisonous substances may be carried away by wind to different places and cause health problems for humans and animals.

Sources: Wars Air pollution is also caused by

• Various types of explosives, Bombs used in wars

• Radioactive emissions from atomic reactors or nuclear explosions pollute air and affect on only present but future generations resulting in deformities…especially in case of accidental leakages.

Natural sources: Volcanic eruptions • Volcanoes can cause air pollution through

release of toxic gases and ash during an eruption.

• Toxic gases : sulfur dioxide, hydrogen sulfide, hydrogen chloride, and hydrogen fluoride. – The carbon dioxide released in a volcanic

eruption can contribute to the greenhouse effect

– sulfur dioxide is a component in acid rain.

Air Pollution

• Global warming.. Greenhouse effect

• Acid rain

• Ozone depletion

• In human population-health problems

- respiratory problem,

- allergies

- risk for cancer…etc

GREENHOUSE EFFECT

Green House Effect- Global warming

Acid Rain

Consequences of Acid rain

Ozone depletion- ozone hole-black hole

Ozone depletion

Ozone hole

Fig. 18-22, p. 491

SOLUTIONS

Stationary Source Air Pollution

Prevention

Burn low-sulfur coal Disperse emissions above thermal inversion layer with tall smokestacks

Remove sulfur from coal

Remove pollutants after combustion Convert coal to a

liquid or gaseous fuel

Shift to less polluting energy sources

Tax each unit of pollution produced

Dispersion or Cleanup

Fig. 18-23, p. 491

SOLUTIONS

Motor Vehicle Air Pollution

Prevention Cleanup

Use mass transit Require emission control devices

Walk or bike

Use less polluting fuels

Improve fuel efficiency

Inspect car exhaust systems twice a year

Get older, polluting cars off the road

Give large tax write- offs or rebates for buying low-polluting, energy efficient vehicles

Set strict emission standards

Remedies: Role of Engines and Fuel

• Different engines and fuel combinations give out different emissions in different quantities.

• Some engines have catalysts which effectively remove part of the harmful gases.

Catalytic Converters and Particle Traps

• Catalytic converters can be fitted to cars to reduce NOx emissions.

CO + HC + NOx H2O + N2 + CO2

Platinum Honeycomb

• Particle traps can be used to reduce PM10 and NOx, but the effectiveness is severely reduced if the fuel the vehicle burns has a high sulphur content.

SOLUTIONS

Air Pollution

Outdoor Indoor

Improve energy efficiency to reduce fossil fuel use

Reduce poverty

Distribute cheap and efficient cookstoves or solar cookers to poor families in developing countries

Rely more on lower-polluting natural gas

Rely more on renewable energy (especially solar cells, wind, and solar-produced hydrogen)

Reduce or ban indoor smoking

Transfer energy efficiency, renewable energy, and pollution prevention technologies to developing countries

Develop simple and cheap tests for indoor pollutants such as particulates, radon, and formaldehyde