Air Pollution

Air Pollution Presented by Dr. B. Victor

About the presenter
Dr.B.Victor is a highly experienced postgraduate biology teacher, recently retired from the reputed educational institution St. Xavier’ s College, Palayamkottai, India-627001.
He was the dean of sciences and assistant controller of examinations.
He has more than 32 years of teaching and research experience
He has taught a diversity of courses ranging from Send your comments to : pre- university to post graduate classes.
[email_address]

Presentation outline
What is pollution?
Kinds of pollution sources
Sources of air pollutants
Kinds of air pollutants
Effects of air pollutants
Green house effect and global warming
Acid rain
Indoor air pollution
Control measures

Gaia hypothesis
The Earth is like a living organism, which itself engaged in a self regulation to support its own "survival"
"The chemical and physical condition of the surface of the Earth, of the atmosphere, and of the oceans has been made fit and is actively made fit and comfortable by the presence of life itself."

This is what earth looks like

Pollution - Definition:
Any addition to air, water, soil etc that threatens the health, survival of humans or other living organisms
1. Natural - volcanic eruption
2. Anthropogenic - burning coal

Types of Sources:
Point source - single, identifiable source e.g. smokestack, drainpipe etc
Non-point source - dispersed source, e.g. runoff from pesticides, fertilizers

Non-point sources

Point source

What are the key environmental problems
A. Population growth B. Resource use without preventing pollution and reducing waste C. Degrading habitats and reduction of biodiversity D. Poverty E. Failure of govt to encourage earth sustaining economic development

The Paul Ehrlich Equation
I = P * A * T = Eye PAT
I mpact = P opulation x A ffluence x T echnology. where: I is the impact on the environment resulting from consumption P is the population number A is the consumption per capita (affluence) T is the technology factor

The Atmosphere
Gases that envelop the Earth and are held here by gravity regulates temperature.
Major gases:
78.08% nitrogen
20.95% oxygen
0.93% argon
0.03% carbon dioxide
trace amounts of water vapor (close to surface) 0.01% by volume near poles to 5% near equator and many others hydrogen, neon, helium, krypton, ozone and methane

Composition of Air

Layers of the atmosphere

Layers of the atmosphere
Troposphere : 75% of mass of air; 17 km thick A turbulent layer of rising and falling air currents.
Stratosphere : extends up to 50 km above the Earth's surface. Less dense, contains nearly 99% of remaining atm.; similar composition. Ozone has a higher volume here (1000 x troposphere), water vapor has a lower volume (1/1000). Calm air. Little vertical mixing.
Mesosphere : 50-90 km
Thermosphere : 90-110 km

Stratospheric ozone layer, O3
.
Formed by a natural process.
Produced by O2 interacting with lightning and UV radiation.
Absorbs most of the shorter wavelengths - UV radiation which is damaging to living things causing cancer, sunburn, cataracts etc.
allows life to live on earth
ozone depletion - a reduction of the ozone layer.

What are the major sources and types of air pollution?

Air pollution :Definition
the presence of one or more chemicals in the atmosphere in sufficient quantities and duration to cause harm to humans etc.

Air Pollution
Air pollution results from human activities such as burning fossil fuels (oil, coal, and gasoline) to create electricity and power automobiles, and manufacture industrial products such as chemicals and plastic.
The air Pollutants are particulates, HC, CO2, CO, NO, NO2, SO3 -- source may be industrial, autos, etc.

Air pollution
The increased carbon dioxide in the atmosphere contributes to the warming of the global climate, the so-called "greenhouse effect."
The increased Chlorofluoro-carbons in the atmosphere has been depleting stratospheric ozone.

Sources of Air pollution
Natural:
volcanoes, fumaroles and hot springs
decay from marshes, bogs
increase ozone due to thunderstorms, fires.

Man made (most severe for human health):
Stationary sources - those that are fixed in location.
point sources e.g. smoke stacks, 14% air pollution from plants generating electricity;
fugitive sources e.g. construction sites, exposed areas;
area sources e.g. dense urban community or agricultural area
Mobile sources - those that move while polluting, e.g. trucks, cars, busses etc. 60% of air pollution from motor vehicles. 80-88% in major cities!

What are the main categories of air pollutants?

The main categories of air pollutants
Primary: those emitted directly into the air; e.g. sulfur dioxide (SO2), carbon monoxide (CO), nitric oxide (NO), nitrogen dioxide (NO2)
Secondary : those that form as a result of a chemical reaction of the primary pollutant with a natural component of the environment.; e.g. some ozone, sulfuric and nitric acids.

Types of pollutants
Primary pollutants
Pollutants that are emitted directly from identifiable sources –produced by both natural events or human activities
Eg. Dust storms, emission from vehicles
Secondary pollutants
When certain chemical reactions take place among the primary pollutants
Eg. Sulphuric acid

Primary pollutants
Carbon oxides (CO2 and CO)
Nitrogen oxides
Sulphur oxides
Volatile organic compounds – hydro carbons
Suspended particulate matter

Primary air pollutants- Auto exhaust
hydrocarbons, methane, butane, propane others.
hydrogen sulfide, H2S, gas. Toxic.
particulates, visible - dust, smoke, soot, very fine <2.5 µm.
lead, batteries, additive to gasoline (phased out). Becomes airborne, spread to land

Primary air pollutants
Sulfur dioxide, SO2 , colorless, odorless gas. particulates of SO4 which combines with water to form acid rain. Toxic to plants and animals; paint damage.
Carbon monoxide CO colorless, odorless gas, readily combines with hemoglobin in blood. Toxic.
Nitrogen oxides, NO, nitric oxide and nitrogen dioxide NO2 . NO2 yellow brown to reddish gas. (NOx) Converted to nitrates in atmosphere causing acid rain.
Photochemical smog , brown air smog. Smog is smoke + fog.

Photochemical Smog
Smog is a kind of air pollution, originally named for the mixture of smoke and fog in the air.
HC and NO react in presence of sunlight to produce ozone and PAN (peroxy acetyl nitrate)
Nitrogen oxides + hydrocarbons + Ultraviolet radiation -----> Peroxyacetyl nitrate PAN + O3 ozone.

Photochemical smog- Effects
breathing ozone results in respiratory distress, headaches.
PAN damages plants
PAH's polynuclear aromatic hydrocarbons, carcinogenic.

Photochemical Smog

What are the effects of air pollution?

The effects of air pollution
reduces visual range and atmospheric clarity, less contrast, less visibility
damage to vegetation, including leaves, needles, fruit, growth rate, reproduction, hardiness.
Decline in net primary productivity NPP.
Crop losses 1.9-5.4 b/yr.

degradation of human health, from mild problems e.g. eye irritation, to severe e.g. respiratory disease asthma, bronchitis, emphysema, cancer.
CO, carbon monoxide , 90% natural, 10% from incomplete combustion, cigarettes, combines with hemoglobin and reduces bloods ability to carry oxygen. 150,000-350,000 deaths/yr.

degradation of vertebrate health, aquatic life, with impacts on respiration, bones, teeth, reproduction; increase lake acidity, decline in NPP
degradation of soil and water, when air pollutants settle, toxic metals in soil, soils leached
deterioration of man-made structures, break down car paint, roofing; acid rain chemically dissolves marble statues and other building materials

Effects of air pollution
Air pollutants can overload or break down the natural defenses such as hair in our nose, sticky mucus in the lining of the upper respiratory tract causing diseases like lung cancer, asthma, chronic bronchitis etc.,

Cigarette smoking is responsible for the greatest exposure to carbon monoxide.Exposure to air containing even 0.001% of carbon monoxide for several hours can cause collapse, coma and even death.
CO is attached to blood hemoglobin reduces the oxygen carrying capacity of blood. This impairs perception and thinking, slows reflexes and causes headaches, drowsiness, dizziness and nausea and blurred vision.

Nitrogen oxides and suspended particles both can irritate lungs, aggravate asthma or chronic bronchitis and increase respiratory infections.
Many volatile organic compounds such as benzene and formaldehyde and toxic particulates such as lead and cadmium can cause mutations, reproductive problems and cancer, breathlessness and irritation of the eye, nose and throat.

Sulphur dioxide irritates respiratory tissues and chronic exposure causes bronchitis.
Sulphur dioxide also reacts with water, oxygen and other materials to form sulphur containing acids – The acids can become attached to particles which when inhaled are very corrosive to the lung.

Chronic exposure of the leaves to air pollutants can break down the waxy coating that helps prevent excessive water loss and leads to damage from diseases, pests, drought and frost.
It also affects photosynthesis, respiration and other metabolisms.

Doubling carbon dioxide

Doubling of carbon dioxide
In 1850, atmospheric carbon dioxide was about 280 parts per million (ppm).
Today, it is about 350 ppm.
This increase is due largely to burning of fossil fuels and clearing of forests.
Oceans (and photosynthetic organisms) currently absorb half of the carbon dioxide emitted.

Carbon dioxide concentration

Increase in carbon dioxide levels between 1960 and 1990.

Increase in the emissions of carbon during the interval from 1860-1995

Concentration of carbon dioxide

Cycle of carbon dioxide

Impact of increasing CO2 levels in the atmosphere
Increased photosynthesis and productivity by the earth’s vegetation .
Increased plant production also means increased respiration .
Elevated atmospheric CO2 is global warming
Elevated CO2 means an increase in global temperature - the greenhouse effect .
Global temperatures may increase by 3oC-4oC by the end of the next century .

Green house effect

Greenhouse gases (GHGs)
Some greenhouse gases occur naturally in the atmosphere, while others result from human activities.
Naturally occuring greenhouse gases include water vapor, carbon dioxide, methane, nitrous oxide, and ozone.

Greenhouse gases (GHGs)
Carbon dioxide is a product of burning fossil fuel and wood.
Nitrous oxide (NO2), produced by fertilizer use and released from decomposition of animal wastes.
Methane (CH4) is produced by bacteria from sediments, swamps, and in flooded rice paddies.
Chlorofluorocarbons (CFCs), Freon (a refrigerant) deplete the ozone layer in the upper atmosphere.
Halons, such as halocarbons), are released from fire extinguishers.
Water vapor in clouds reradiate heat back to Earth.

Green house gas emissions

Greenhouse gases

Green house effect
Carbon dioxide and other gases allow light to pass, but trap heat in the atmosphere much like glass in a greenhouse traps heat.
This greenhouse effect is thought to be responsible for global warming.
Carbon dioxide contributes to only 56% of greenhouse heating.
The average surface temperature of Earth is about 15°C (59°F).
Global Warming is increase in the average temperature of the atmosphere, oceans, and landmasses of Earth.
A A

Greenhouse effect

Impact of Global warming
Temperature extremes
Rise in sea level, and change in precipitation
Injuries from storms, coastal flooding
Interruption of power supply, contamination of drinking water
Drought
Food shortages due to shift in agricultural food production
Air pollution ( made worse by warming)
Asthma, bronchitis, emphysema complications
Strain on public health systems
Increased need due to population migrations
Unable to contain spread of infectious diseases

Conserve Energy
Be energy-wise
Explore alternatives
Recycle as much as is possible.
Take showers instead of baths.
Check your taps.
Check the lights
Check your stove.
Use less cooking water.
Check the refrigerator.

Ozone depletion

Ground level Ozone
Ozone (O3) is a key constituent of the troposphere.
Ozone (Greek ozein, “to smell”), pale blue, highly poisonous gas with a strong odor.
Ozone is considered a pollutant at ground level.
Breathing O3 affects both the respiratory and nervous systems, resulting in respiratory distress, headache, and exhaustion.
Ozone is damaging to plants, resulting in leaf mottling and reduced growth.

The Ozone Layer
Earth's atmosphere consists of a number of different layers.
The troposphere is the lower atmospheric layer.
The stratosphere is often referred to as the upper atmosphere.
The stratosphere contains the ozone shield, a layer of ozone (O3) in the stratosphere, 50 km above the ground.

The Ozone Layer

Hazards of UV radiation
Hazards of UV radiation include increased mutation rate, which can lead to skin cancer and cataracts, depression of the immune system, impaired crop and tree growth, and the death of plankton.

Health effects of Ozone depletion
Each 1% drop in ozone is thought to increase human skin cancer rates by 4-6%.
The United Nations Environment Program predicts a 26 percent rise in cataracts and non-melanoma skin cancers for every 10% drop in ozone.
This translates to 1.75 million cases of cataracts and 300,000 more cases of skin cancer every year.

Ozone Hole above Antarctica
During the 1980s scientists discovered a "hole" in the ozone over Antarctica.
By the 1990s atmospheric scientists had detected an annual loss of 40-50% of the ozone above Antarctica, which produced an ozone hole every spring.
One CFC molecule can destroy 100,000 ozone molecules.

The largest Antarctic ozone hole ever recorded (September 2006).
The Antarctic ozone hole is an area of the Antarctic stratosphere in which the recent ozone levels have dropped to as low as 33% of their pre-1975 values.

What is acid rain; what are its causes and effects?

Environmental Impact of Acid deposition
Sterilization of lakes and forests.
Reducing the populations of small invertebrates and decomposers.
Reducing agricultural yields.
Causing extensive structural damage by corroding marble, metal, and stonework.
Degrading water supplies by leaching heavy metals from the soil into drinking-water supplies.
Increases in lung cancer and colon cancer.

Wet and dry acid deposition
Caused by SO2 and NO2. Alone cause dry acid deposition, with all forms of water vapor, these form sulfuric and nitric acid - acid rain downwind of sites of emission.
Logarithmic scale. pH of 4 is 10 x more acidic than pH of 5. Normal rain water pH 5.0-5.6 approx. Acid rain < 5.0 Affects industrialized areas worldwide. Scandinavia, Eastern Europe, N.E. U. S. Developing countries have more pollution, fewer controls than developed countries.

Acid Precipitation

Acid rain
The term "acid rain" is commonly used to mean the deposition of acidic components in rain, snow, fog, dew, or dry particles.
The more accurate term is "acid precipitation.“
"Clean" or unpolluted rain is slightly acidic, its pH being about 5.6, because carbon dioxide and water in the air react together to form carbonic acid, a weak acid.
H 2 O + CO 2 -> H 2 CO 3 (aq)
The extra acidity in rain comes from the reaction of primary air pollutants, primarily sulfur oxides and nitrogen oxides, with water in the air to form strong acids (like sulfuric and nitric acid).
The main sources of these pollutants are vehicles and industrial and power-generating plants.

Acid Rain
Nitric oxide & sulfur dioxide released primarily from electric power plants & motor vehicles
SO 2 + water vapor + ozone ---> H 2 SO 4
NO + sunlight + O 2 ---> NO 2 + various atmospheric gases ---> HNO 3

Effects of Acid Rain
Acidify lakes and disrupt the normal cycling of nutrients,
leaches metals out of rocks and soil,
kill fish, plants; stress and defoliate trees due to moss growth, insect attack, and loss of nutrients.

Acid rain - causes
The principal cause of acid rain is sulfur - and nitrogen compounds from human sources, such as electricity generation , factories and motor vehicles . Coal power plants are one of the most polluting.

What are the sources of indoor air pollution?

Sources of indoor air pollutants
building materials,
cigarette smoking,
pesticides,
volatile organics from paints, furniture, rugs, insulation etc.

Sources of indoor air pollution
11 common pollutants 2-5 times higher indoors than out
air inside car 18 times more polluted than air outside
17% of commercial buildings have serious indoor air pollution problems - sick building syndrome

Are there any natural indoor air pollutants?
Radon gas accumulates in homes located in areas built on granites, phosphates, shales.
Synergistic effect with tobacco smoke; second leading cause of lung cancer
Sources: soils, groundwater, building materials.
Cannot be filtered out. Must be vented out.

Most dangerous indoor air pollutants
Cigarette smoke
formaldehyde
radioactive radon 222 gas
asbestos
Others include: bacteria, fungi, dusts and other particulates, pollen, CO2, CO, O3, NOx, SO2, building materials such as fiberglass, etc.

Suggestions for the future:
pollution prevention
full cost pricing i.e. shift costs to the production of air pollutants
improve energy efficiency
reduce use of fossil fuels
slow population growth

How serious is the problem of indoor air pollution?
People with respiratory ailments are most affected Asbestos inhalation may cause: asbestosis, lung cancer, mesothelioma.
Asbestos workers, insulators pipe fitters, shipyard employees.

What are some of the symptoms of indoor air pollution?
Irritation of mucous membranes,
coughing,
dizziness,
nausea,
death.

General solutions:
switch from coal to cleaner fuels - use natural gas
reduce energy use, improve energy efficiency
burn less coal, use lower sulfur coals. Coal gasification
After burning the SO2 can be cleaned out by scrubbing
taxing emissions

General solutions to indoor air pollution:
Ventilation: fans
source removal: no smoking
source modification: more efficient stove design.
pollutant removal: filters
education

What are the special problems associated with urban areas?

Urban trends:
discourage auto use, reduce number of cars
stricter emission controls
require electric cars
improve public transport
mandatory carpools
industrial & household controls
reduce emissions- burn less fuel, be energy efficient
control NOx by recirculating exhaust
catalytic converters removes CO and hydrocarbons by converting to CO2 and water
effluent fees and emissions tests to assure catalytic converters are maintained

Special problems associated with urban areas
Meteorological conditions along with topography can affect air pollution.
Natural ventilation occurs when winds are strong and turbulent, mixing is good, large mixing volume.
atmospheric inversion- temperature inversion, warmer air above cooler air, prevents dissipation of pollutants. pollutants collect, no wind.

Urban air pollution
Urban air pollution determined by:
rate of emission per unit area
distance downwind that a mass of air can move
wind speed
height of mixing

Thank you

http://bonvictor.blogspot.com	163
http://www.slideshare.net	20
http://bonvictor.blogspot.com.au	3
http://bonvictor.blogspot.it	1
http://bonvictor.blogspot.in	1

Air Pollution

by Dr.Victor on Dec 20, 2009

Accessibility

Categories

Tags

Upload Details

Usage Rights

5 Embeds 188

Statistics

Air Pollution — Presentation Transcript