MODULE 2

AIR POLLUTION• Any visible or invisible particle or gas found in the air that

is not part of the original, normal composition.AQI: Air Quality Index• Indicates whether pollutant levels in air may cause health

concerns.• Ranges from 0 (least concern) to 500 (greatest concern)

Sources of Air Pollution• Natural & Anthropogenic

• Motor vehicular exhaust• Power stations• Demolition of buildings• Road construction• Industries• Volcanic eruptions• Forest fires(natural and man made)

Types of air pollution1. Natural air pollution and anthropogenic air pollutionNatural sources of air pollution• Volcanoes: Volcanic activity produces smoke, ash, carbon

dioxide, sulfur dioxide etc.• Dust: Wind blown dust from areas with little or no vegetation

such as desert areas.• Forest Fires: Forest fires created by natural causes result in

the formation and release of smoke, ash, dust, carbon dioxide, nitrogen oxide and other air pollutants.

• Wetlands: Microbial action in wetlands result in significant amounts of methane being formed and released to the atmosphere.

Anthropogenic air pollution sources• Stationary point sources: A stationary point source is

single, identifiable sources of air pollutant emissions. For example, the emissions from a combustion furnace flue gas chimney/stack.

• Mobile sources: mobile sources include the exhaust emissions from vehicles.

• Evaporative sources: evaporative sources are volatile liquids that when not completely enclosed in a tank or other container, evaporate and release vapors over time. For example, liquids such as paints, solvents, pesticides, perfumes, hair sprays etc.

Primary Pollutants

CO CO2Secondary Pollutants

SO2 NO NO2Most hydrocarbons SO3

Most suspended particles HNO3 H2SO4

H2O2 O3 PANs

Sources Natural Stationary

Mobile

Most NO3− and SO4

2− salts

2. Outdoor air pollution and indoor air pollution• Outdoor air pollution is primarily due to automobile exhaust and

industrial emissions and indoor air pollutants are released by indoor activities such as smoking, cooking, painting so on and so forth.

• The major outdoor air pollutants are known as Big Six Criteria air pollutants which are the oxides of nitrogen, oxides of sulphur, ground level ozone, particulate matter ( and ), carbon monoxide and lead vapour.

3. Primary air pollution and secondary air pollution• Primary air pollutants are substances that are emitted directly into

the atmosphere and they exist in the same form,(such as CO, CO2,SO2,H2S etc.) as in source emissions.

• Secondary air pollutants are formed in the atmosphere by the interaction of two or more primary air pollutants or by the reaction of primary air pollutant with other elements in the atmosphere with or without photo activation. Examples are ozone, formaldehyde, (PAN) etc.

4. Air pollution caused by Hazardous air pollutants• Hazardous air pollutants are toxic air pollutants that can cause

serious health effects such as cancer, birth defects, neurological health issues and reproductive problems. Some of them are heavy metals, asbestos, formaldehyde(in paints and solvents), vinyl chloride (in plastics) etc.

5. Particulate matter pollution and gaseous air pollution• Particulate matter (PM) consists of materials like dust, smoke and

soot. Particles larger than 10mm are trapped in the nose itself. Particles between 5mm and 10mm are removed by physical processes in the throat. Particles smaller than 5mm reach bronchial tubes, while particles 2.5mm in diameter or smaller are breathed into deepest portions of the lungs (which is very dangerous).

• Gaseous pollutants: the major gaseous pollutants include SO2, NOx, CO as well as ground level ozone(O3). Each of these pollutants, in their gaseous form can cause harm to human health and the environment.

6. Air pollution caused by volatile organic compounds(VOCs)

• VOCs are defined as organic compounds which easily evaporate (at room temperature) and enter the atmosphere. Some of the common examples include acetone, benzene, ethylene glycol, formaldehyde, toluene, xylene etc.

5 Major Pollutants:1.) Carbon Monoxide2.) Sulfur Dioxide3.) Nitrogen Dioxide4.) Particulate Matter5.) Ground Level Ozone

Carbon Monoxide• colorless, odorless• produced when carbon does not burn in fossil fuels• present in car exhaust• causing headaches, fatigue, and impaired vision

Sulfur Dioxide• produced when coal and fuel oil are burned• present in power plant exhaust• narrows the airway, causing wheezing and shortness of

breath, especially in those with asthma

Nitrogen Dioxide• reddish, brown gas• produced when nitric oxide combines with oxygen in the atmosphere• present in car exhaust and power plants• affects lungs and causes wheezing; increases chance of respiratory

infection

Particulate Matter• particles of different sizes and structures that are released into the

atmosphere• present in many sources including fossil fuels, dust, smoke, fog, etc.• can build up in respiratory system• aggravates heart and lung disease; increases risk of respiratory

infection

Ground Level Ozone• at upper level, ozone shields Earth from sun’s harmful UV rays• at ground level, ozone is harmful pollutants• formed from car, power and chemical plant exhaust• irritate respiratory system and asthma; reduces lung function

by inflaming and damaging lining of lungs

Smoge

• Combination of gases with water vapor and dust• Combination of words smoke and fog• Forms when heat and sunlight react gases

(photochemical smog)• Occurs often with heavy traffic, high temperatures, and

calm winds

• 1st smog related deaths were in London in 1873; death toll 500 people

• Limits visibility• Decreases UV radiation• Yellow/black color over cities• Causes respiratory problems and bronchial related deaths

Effects of air pollution• Effects of air pollution on health

o Eye irritationo Nose and throat irritationo Increase in morality rate morbidity rateo Chronic pulmonary diseases like bronchitis and asthmao Carbon monoxide readily combines with hemoglobin in blood thus

replacing oxygen from bloodo Carcinogenic agents cause cancer

• Effects of air pollution on plants and animalso Suppressed growth and premature ageing in plantso Leaf bleaching (reduced efficiency of photosynthesis)o Acid deposition can damage aquatic lifeo Respiratory problems in animalso Migration of seasonal birds are hampered due to severe air

pollution

• Effects of air pollution on environment and propertyo Reduces visibility due to smog formationo Acid deposition can corrode metals, eat away stone on statues and

monumentso Discolor buildings, cloth fabrics

Specific pollutants Effects of pollutantsSulphur dioxide Affects the mucous membrane when inhaled

Carbon monoxide It has a strong affinity for combining with hemoglobin of blood to form carboxy hemoglobin

Oxides of nitrogen It causes eye and nasal irritation. Also it causes pulmonary discomfort

Hydrogen Sulphides and mercaptans

Causes fatigue of the sense of smell and is odorous

Ozone Irritant action in the respiratory tract

Fluorides It is a cumulative poison

Lead Gastro intestinal damage, liver and kidney damage, abnormalities in fertility & pregnancy, and mental development of children gets affected

Hydrocarbon vapours Eye and respiratory irritation caused by photochemical smog

Control measures to reduce air pollution

• Determine the priority air pollutants – based on health effect and the severity of the air quality problem

• Incorporate the control measures into a plan with implementation dates to formalize the strategy

• Involve the public in air quality management activities as a part of the strategy development process

• Afforestation programs• Periodic air quality monitoring• Adoption of stringent pollution control measures• Reduction in the use of conventional fuels• Promotion of use of renewable energy sources.

WATER POLLUTIONSources of water pollution• Point Source

• Sources which can be readily identified at a single location (direct discharge from a single point). Examples are industrial discharges, municipal sewage etc. water pollution caused by these sources can be minimized if the effluents from these sources are controlled, treated up to acceptable levels and disposed off.

• Non-point source or Diffused sources• Non point sources are diffused across a broad area and their

contamination cannot be traced to a single discharge point. Here the pollutants scattered on the ground ultimately reach the water sources and cause pollution, like run off from the agricultural lands, mining area etc.

Point Source

Non point source

NONPOINT SOURCES

Urban streets

Suburban development

Wastewater treatment plant

Rural homes

Cropland

Factory

Animal feedlot

POINT SOURCES

• Natural sources• Rain water• Atmosphere• Surrounding vegetation• Underground rocks and volcanoes• Natural run-off

• Anthropogenic sources • Domestic wastewater• Agricultural runoff• Industrial effluentDomestic wastewater

Domestic sewage is the wastewater generated from the household activities that originate from residential areas, commercial places, institutions and other public places

• Agricultural wastewaterThis is the run off from the agricultural fields and

animal farm and this wastewater is considerably rich in• Nitrogen • Phosphate• Organic matter• Pesticides

• Industrial wastewaterIndustrial wastes are the one which results from industrial operations. Each year, the world generates around 400 billion tons of industrial waste, much of which is pumped untreated into rivers, oceans and other waterways. Industrial waste water may have pollutants of almost all kinds ranging from simple nutrients and organic matter to complex toxic substances.

Water pollutants 1. Inorganic substances

These include Nitrates, Phosphates, carbonates, chlorides, sulphates of Ca, Mg, FE etc. These salts makes water hard. Hard water increases soap consumption and deposits scales on pipelines. Iron causes spots and stains on white fabrics.2. Organic matter

Organic pollution occurs when large quantities of organic compounds which act as substrates for microorganisms, are released into water sources. During the decomposition of organic pollutants, the dissolved oxygen in the receiving water may be used up at greater rate than it can be replenished, causing oxygen depletion.

3. Thermal dischargesIncrease in the normal temperatures of natural water

is caused by nuclear power plant/ boiler/ industrial discharges, where water is used as a cooling agent. Elevated water temperatures decrease oxygen levels, which can kill fish and alter food chain composition and reduce species biodiversity.4. Floating matter

These include oils, greases and other materials which float on the surface, and make the river unsightly and obstruct passage of light through the water.5. Toxic chemicals

These include cyanides, sulphides, acetylene, alcohol etc. Many of these have cumulative effect on the flora and fauna.