Sources of air pollution

    TOBACCO SMOKE contains carbon monoxide, tar and nicotine which increases heart attacks and causes cancer.

    MINING ACTIVITIES lead to rock particles, coal and mineral dust that cause lung and respiratory ailments.

    CARBON MONOXIDE & LEAD from exhausts of motor vehicles affect the brain and organs like the kidney.

    POISONOUS GASES from factories and chemical plants cause respiratory diseases.
 

DECOMPOSING GARBAGE AND OPEN SEWERS emit methane and hydrogen sulphide. Exposed garbage and sewers are a breeding ground for mosquitos, files, germs and bacteria.

    SMOKE FROM BURNING FUELS AND OIL RIGS cause global warming and impure air. Smoke contains benzopyrene which causes cancer.

Domestic Pollution

The worst form of air pollution could be the wood smoke inhaled by women while cooking.
 

Automobile Pollution

The vehicular population is of three principal types:

The major emissions from a gasoline powered engine are mainly carbon monoxide (CO), unburned hydrocarbons (HC), oxides of nitrogen (NOx) and others like formaldehyde, acetaldehyde, acrolein and benzaldehyde. Among the particulates, lead is the major significant toxic compound. Indian petrol contains a high percentage of lead, whose emission leads to lung diseases and cancer.

Thermal Power Stations

All thermal power plants are coal-fired. The major effluents from these plants are fly ash, soot and sulphur dioxide. The sulphur content of Indian coal is less than one percent. But the coal contains a high ash content, in the range of 25 % to 40 %. Fly ash from power stations reduces visibility and contains traces of chromium, arsenic, cadmium, mercury, lead, manganese, etc. Once again, these affect human health.

Fertiliser Factories

Fertiliser plants produce large quantities of air pollutants. Some of them are fluorine, ammonia, sulphur dioxide, nitrogen oxides and particulates. Although fertilisers are essential for boosting agricultural production, their production has many ill effects, such as health-affecting emission of gases, etc.

Textile Mills

The major effluents from textile mills are cotton dust, smoke and other combustion wastes, kerosense or naptha vapours, sulphuric acid, nitrogen oxide, chlorine, formaldehyde, etc. The surroundings of textile mills are generally dusty with deposits of cotton fluff. Continuous inhalation of cotton fluff causes lung disorders.

- Courtesy by : C.P.R.Environmental Education Centre, Chennai               

Modernisation and progress have led to air getting more and more polluted over the years. Industries, vehicles, increase in the population, and urbanization are some of the major factors responsible for air pollution. The following industries are among those that emit a great deal of pollutants into the air: thermal power plants, cement, steel, refineries, petro chemicals, and mines.

Air pollution results from a variety of causes, not all of which are within human control. Dust storms in desert areas and smoke from forest fires and grass fires contribute to chemical and particulate pollution of the air. The source of pollution may be in one country but the impact of pollution may be felt elsewhere. The discovery of pesticides in Antarctica, where they have never been used, suggests the extent to which aerial transport can carry pollutants from one place to another. Probably the most important natural source of air pollution is volcanic activity, which at times pours great amounts of ash and toxic fumes into the atmosphere.


National Ambient Air Quality Standards

POLLUTANTS

AVERAGE TIME  

CONCENTRATION  

 

Sulphur dioxide (SO2)

 

Annual average

 

60 µg/m3

 

24 hour

80 µg/m3

   

  

  

Oxides of Nitrogen (NO2)

A.A

60 µg /m3

 

24H

80 µg /m3

  

  

  

Suspended Particulate Matter (SPM)

A.A

140 µg/m3

 

24H

200 µg/m3

  

  

  

Lead

A.A

0.75 µg/m3

  

24H

1.0 µg/m3

  

  

  

Carbon Monoxide

A.A

2.0 µg/m3

  

24H

4.0 µg/m3

  

 

 

Respirable Particulate Matter (RPM)

A.A

60 µg/m3

  

24H

100 µg/m3

  

  

  

Listed below are the major air pollutants and their sources.

Carbon monoxide (CO)is a colourless, odourless gas that is produced by the incomplete burning of carbon-based fuels including petrol, diesel, and wood. It is also produced from the combustion of natural and synthetic products such as cigarettes. It lowers the amount of oxygen that enters our blood . It can slow our reflexes and make us confused and sleepy.

Carbon dioxide (CO2)is the principle greenhouse gas emitted as a result of human activities such as the burning of coal, oil, and natural gases.

Chloroflorocarbons (CFC) are gases that are released mainly from air-conditioning systems and refrigeration. When released into the air, CFCs rise to the stratosphere, where they come in contact with few other gases, which leads to a reduction of the ozone layer that protects the earth from the harmful ultraviolet rays of the sun.

Leadis present in petrol, diesel, lead batteries, paints, hair dye products, etc. Lead affects children in particular. It can cause nervous system damage and digestive problems and, in some cases, cause cancer.

Ozone occur naturally in the upper layers of the atmosphere. This important gas shields the earth from the harmful ultraviolet rays of the sun. However, at the ground level, it is a pollutant with highly toxic effects. Vehicles and industries are the major source of ground-level ozone emissions. Ozone makes our eyes itch, burn, and water. It lowers our resistance to colds and pneumonia.

Nitrogen oxide (Nox) causes smog and acid rain. It is produced from burning fuels including petrol, diesel, and coal. Nitrogen oxides can make children susceptible to respiratory diseases in winters.

Suspended particulate matter (SPM) consists of solids in the air in the form of smoke, dust, and vapour that can remain suspended for extended periods and is also the main source of haze which reduces visibility. The finer of these particles, when breathed in can lodge in our lungs and cause lung damage and respiratory problems.

Sulphur dioxide (SO2) is a gas produced from burning coal, mainly in thermal power plants. Some industrial processes, such as production of paper and smelting of metals, produce sulphur dioxide. It is a major contributor to smog and acid rain. Sulfur dioxide can lead to lung diseases.

- Courtesy by : edugreen.teri.res.in

The two main classification of sources are:

Point Source Emissions

Point sources include industrial and nonindustrial stationary equipment or processes considered significant sources of air pollution emissions. A facility is considered to have significant emissions if it emits about one ton or more in a calendar year. Examples of point sources include industrial and commercial boilers, electric utility boilers, turbine engines, wood and pulp processers, paper mills, industrial surface coating facilities, refinery and chemical processing operations, and petroleum storage tanks. Area sources that may fall under the point source definition are piping leaks, industrial wastewater treatment ponds, rock and quarry operations, and tank farms. Insignificant point sources are included by category in the area source inventory.

The most accurate method for determining the amount of emissions produced by a facility is with continuous emissions monitoring. However, this is expensive and not always practicable. Emissions are estimated using a variety of methods. Standard methods of estimating point source emissions are available from the EPA in the Compilation of Air Pollutant Emission Factors, Volume I, also known as AP-42. Other methods include stack testing, equipment vendor test data, material balances such as for surface coating, or TNRCC-approved permit factors. If no other method is available, then the best engineering judgment must be used.

Facilities report point source emissions to the TNRCC for the calendar year and the data are stored in the Point Source Database. Data are available for use by TNRCC staff, the EPA, state and federal legislators, air pollution researchers, public interest groups and the general public.
 

Emissions from Non-Point Sources

On-Road Mobile Sources

Emissions from on-road mobile sources are estimated using a sophisticated model called MOBILE, which was developed by the Environmental Protection Agency (EPA). MOBILE calculates an emissions factor for mobile sources using a set of complex mathematical equations that require several user input values.

Vehicles are segregrated into eight vehicle classes with MOBILE generating an emissions factor for each class and a composite emissions factor representing all classes.

On-Road Mobile Source Vehicle Classes

After an emissions factor is generated for each vehicle classes, the factor is then used in conjunction with the vehicle miles traveled (VMT) estimates, which were developed with the Texas Highway Performance Monitoring System (HPMS) data set for that selected area. This combination determines the contribution of emissions from mobile sources in a city, county, or state.

Non-Road Mobile Sources

Non-road mobile sources include a wide variety of internal combustion engines not associated with highway vehicles. Emissions calculation methodology is as varied as the categories themselves. A federal computer model using engine types and landing/takeoff cycles is used to calculate most aircraft emissions. Actual fuel usage and track mileage are applied to determine locomotive emissions. Ship and barge traffic data is used to calculate emissions from ocean vessels.

Non-road Mobile Source Categories:

Aircraft:
Commercial
Military
 

 

General:
Locomotives
Vessels (ships and barges)

Small engines:
Lawn and garden
Airport support vehicles
Recreational marine
Light commercial
Industrial construction
Agricultural logging

Area Sources

Area source inventories generally report emissions by categories rather than by individual source; a common method in reporting point source emissions. Area source emissions are calculated by various methods and depend on the type of data available for each category. For example, whenever fuel use and materials data are not available, employee and county population numbers are used with established emission factors to calculate emissions. Emissions are calculated and reported on a county-wide basis.

Major categories of area sources are:

Biogenic Sources

Biogenic emissions account for 30 percent of all the volatile organic compounds (VOCs) emitted in urban areas in the eastern half of Texas. For the purposes of photochemical modeling, biogenic VOC emissions are estimated using a computer model that takes into account the species of trees present, the density of their foliage, the temperature and solar radiation on the day in question, and the distribution of vegetation throughout the modeling domain. It is important to measure these parameters accurately if the biogenics inventory is to be correct. The TNRCC has hired specialists to measure some of these variables in north-central and southeastern Texas.

Most plants emit some VOCs, but the largest emitters are oaks, pines, sweet gums, eucalyptus, and poplars. Some VOCs are easily detected by their aroma. Pines, sycamores, and eucalyptus emit fragrant monoterpenes while other VOCs such as isoprene are not as aromatic.

Isoprene is a byproduct of photosynthesis. Scientists still debate the purpose of its emission but some evidence suggests that plants can cope better with heat if isoprene is present. Because it is generated by photosynthesis, isoprene emissions are not generated at night.

Monoterpenes are known as "essential oils." There is solid evidence that plants make monoterpenes, which are found in small reservoirs in the leaves or needles of plants, to ward off herbivores. When an insect feeds on the leaf, the monoterpenes are released and can adversely affect the insect's health. Because the monoterpenes are always present in the leaves, their emission rate depends mostly on the temperature. Higher temperatures will evaporate larger amounts into the atmosphere.

There are a few other important organic compounds emitted by plants. Alcohols are often emitted by damaged vegetation; there is some evidence that these alcohols act as an antiseptic. A few recent studies suggest that alkenes are also emitted by some plants.
 

- Courtesy by : Texas Natural Resource Conservation Commission.