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Air Pollution i.

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Presentation on theme: "Air Pollution i."— Presentation transcript:

1 Air Pollution i

2 Exosphere Thermosphere Mesosphere Stratosphere Troposphere

3 Primary pollutants: are mixed vertically and horizontally and are dispersed and diluted by the churning air in the troposphere. Ex: CO, CO2, SO2, NO, NO2, most hydrocarbons, and most suspended particles Secondary pollutants: while in the troposphere, some of the primary pollutants may react with one another or with the basic compounds of air. Ex: SO3, HNO3, H2SO4, H2O2, O3, and PANs

4 Six Principal Pollutants
- Carbon Monoxide (CO) - Lead (Pb) - Nitrogen Dioxide (NO2) - Ozone (O3) - Particulate Matter (PM-10) - Sulfur Dioxide (SO2)

5 Ozone Ozone is formed by the action of sunlight on carbon-based chemicals known as hydrocarbons, acting in combination with a group of air pollutants called oxides of nitrogen. Ozone reacts chemically ("oxidizes") with internal body tissues that it comes in contact with, such as those in the lung. Ozone (O3) in the troposphere causes more damage to plants than all other air pollutants combined.

6 SO2 Sulfur dioxide belongs to the family of gases called sulfur oxides (SOx ). These gases are formed when fuel containing sulfur (mainly coal and oil) is burned, and during metal smelting and other industrial processes. The major health concerns associated with exposure to high concentrations of SO2 include effects on breathing, respiratory illness, alterations in pulmonary defenses, and aggravation of existing cardiovascular disease.

7 SO2 Emissions

8 Lead In the past, motor vehicles were the biggest source of lead. But since leaded gasoline has been phased out, lead emissions have decreased by about 98 percent. Today, metal processing is the biggest source of atmospheric lead. Lead can harm the kidneys, liver, nervous system and other organs. It may cause neurological impairments such as seizures, mental retardation and behavioral disorders. Even at low doses, lead is associated with damage to the nervous systems of fetuses and young children, resulting in lowered IQ and learning problems.

9 Particulates Particulates is a general term used to describe tiny bits of matter floating around in the atmosphere, such as certain types of smoke (like diesel smoke), fine ash and dust. Larger particles are caught by the hairs in your nose and your breathing tubes, but smaller particles can get past these defenses and cause lots of trouble.

10 NO2 Nitrogen dioxide belongs to a family of highly reactive gases called nitrogen oxides (NOx). These gases form when fuel is burned at high temperatures, and come principally from motor vehicle exhaust and stationary sources such as electric utilities and industrial boilers. Nitrogen dioxide can irritate the lungs and lower resistance to respiratory infections such as influenza.

11 Carbon Monoxide Carbon Monoxide is produced by the incomplete combustion of the fossil fuels – gas, oil, coal and wood used in boilers, engines, oil burners, gas fires, water heaters, solid fuel appliances and open fires. When carbon monoxide is present in the air you breath into your lungs, it attaches itself to the hemoglobin. The bond between hemoglobin and carbon monoxide is 250 times stronger than oxygen. In the lungs carbon monoxide attaches to red blood cells in place of oxygen.

12 Smog (smoke+fog)

13 The Four Most Dangerous Indoor Air Pollutants
cigarette smoke Formaldehyde Asbestos radioactive radon-222 gas

14 Formaldehyde Formaldehyde is a colorless liquid or gas with a strong, distinctive odor. It is found in furniture, new carpets, particle board, plywood, rubber cement and adhesives. Low levels of exposure can irritate the eyes, nose and throat, cause skin problems, serious breathing problems and can increase your risk of certain kinds of cancer.

15 ASBESTOS Sources: Deteriorating of damaged insulation, fire-proofing, or acoustical materials. Health Effects: No immediate symptoms. Chest and abdominal cancers and lung diseases. Smokers are at higher risk of developing asbestos-induced lung cancer.

16 RADON Sources: Earth, uranium and rock beneath home; well water; building materials. Health Effects: No immediate symptoms. Estimated to cause about 10% of lung cancer deaths. Smokers are at higher risk of developing radon-induced lung cancer.

17 Radon-222 can enter the house by diffusion from soil and by emanation from building materials, tap water and methane gas. Characteristics - an odorless, tasteless, invisible gas that mixes with air - chemically inert and essentially non-reactive - heaviest noble gas with highest melting and boiling point - highly soluble in non-polar solvents - moderately soluble in cold water - able to diffuse through rock and soil - decays by alpha particle emission (T 1/2 = 3.8 days)

18 The largest source of "indoor air pollution"- in our homes, our schools or workplaces- is car and truck pollution. Electric vehicles are sometimes referred to as "zero-emission vehicles" because they produce essentially no pollution from the tailpipe or through fuel evaporation. This is important, for it means that the use of electric vehicles could greatly reduce emissions of carbon monoxide and smog-forming pollutants in cities with dirty air.

19 Symptoms (IAP) As many as 20 million Americans suffer from:
chronic breathing problems dizziness rash headaches sore throat sinus eye irritation


21 Acid Deposition: the falling of acids and acid-forming compounds from the atmosphere to earth’s surface. Acid deposition is commonly known as acid rain, a term that refers only to wet deposition of droplets of acids and acid-forming compounds Effects of Acid rain human respiratory disease (bronchitis and asthma) damages statues, buildings, metals, and car finishes depletion of calcium and magnesium ions in the soil damages trees

22 How to reduce acid deposition
Reduce energy use and thus air pollution by improving energy efficiency Switch from coal to cleaner burning natural gas and renewable energy resources Remove sulfur from coal before it is burned Burn low-sulfur coal Remove SO2, particulates, and nitrogen oxides from smokestack gases Remove nitrogen oxides from motor vehicle exhaust

23 Sick Building A building is considered “sick” when at least 20% of its occupants suffer persistent symptoms that disappear when they go outside At least 17% of the 4 million commercial buildings in the U.S. are considered “sick”.

24 Ozone Most ozone (about 90%) exists in the stratosphere, in a layer between 10 and 50km above the surface of the earth. This ozone layer performs the essential task of filtering out most of the sun's biologically harmful ultraviolet (UV-B) radiation.

25 Ozone Hole Over Antarctica (and recently over the Arctic), stratospheric ozone has been depleted over the last years at certain times of the year. This is mainly due to the release of manmade chemicals containing chlorine such as CFC's (ChloroFluoroCarbons), but also compounds containing bromine, other related halogen compounds and also nitrogen oxides (NOx).

26 CFC’s CFC's are chemicals that can be used in the refrigerator to help keep food cold They can also be used in air conditioning and in products in spray cans. CFC's rise into the air going into a layer called the stratosphere. When this happens, the CFC's take part in chemical reactions that can destroy parts of the ozone which protects us from the sun's dangerous ultraviolet rays.

27 Ozone Hole

28 Greenhouse Effect The Earth is kept warm by it's atmosphere, which acts rather like a woolly coat - without it, the average surface temperature would be about -18 degrees Centigrade. Heat from the sun passes through the atmosphere, warming it up. As the Earth warms up, it emits heat. Some of this heat is trapped by the atmosphere, but the rest escapes into space. The so-called "greenhouse gases" make the atmosphere trap more of this radiation, so it gradually warms up more than it should, like a greenhouse.

29 Greenhouse Effect

30 Greenhouse Effect Ozone Shield Where in the atmosphere does it occur?
Troposphere Stratosphere What process occurs? Traps heat near the earth’s surface Filters ultraviolet (UV) radiation from the sun What natural gases are involved? Water(H2O), carbon dioxide(CO2), methane(CH4) Oxygen(O2), ozone(O3) What are important human inputs? Carbon dioxide(CO2), methane (CH4), chlorofluorocarbons (CFCs), nitrous oxide(N2O) Chlorofluorocarbons (CFCs), halons, carbon tetrachlorine, methyl choloroform (stable), halogen-containing gases What problems result? Global warming Ozone depletion

31 Carbon Dioxide Carbon dioxide is produced when any form of carbon or almost any carbon compound is burned in an excess of oxygen. For example, it is released into the atmosphere during natural forest fires and the man-made combustion of fossil fuels. Other natural sources of carbon dioxide include volcanic eruptions, decay of dead plant and animal matter, evaporation from the oceans and respiration (breathing).

32 Methane Methane is a greenhouse gas that is creating a serious problem for global warming. Methane gases are very potent when trapping infrared heat in the atmosphere, because one molecule of methane can trap infrared heat twenty times more than carbon dioxide. Methane the second most important greenhouse gas is mostly produced by the digestive system of cows.


34 Asthma Smog and particles certainly trigger attacks in some people who already have asthma. For a long time it was thought that air pollution could not cause asthma to develop in previously healthy people. Some recent experiments challenge this belief. Scientists have shown that people exposed to ozone or nitrogen dioxide are more likely to react to allergens such as grass pollens and housedust mites than those who are not exposed. Thus a combination of air pollution and allergens could cause some cases of asthma.

35 Lung Cancer Lung cancer is more common in cities than in the country. We know that over 90% of lung cancers are caused by smoking cigarettes. A radioactive gas called radon is thought to cause about 7% of lung cancers in North America.

36 87% of lung cancer cases are caused by smoking
87% of lung cancer cases are caused by smoking. 12 percent of all lung cancer deaths are linked to radon. Another leading cause of lung cancer is on-the-job exposure to cancer-causing substances or carcinogens.

37 Air pollution can make you sick
Air pollution can make you sick. It can cause burning eyes and nose and an itchy, irritated throat, as well as trouble in breathing. Some chemicals found in polluted air cause cancer, birth defects, brain and nerve damage and long-term injury to the lungs and breathing passages. Some air pollutants are so dangerous that accidental releases can cause serious injury or even death.

38 According to the U.S. Environmental Protection Agency's (EPA) latest Ten-Year Air Quality and Emissions Trends report, there have been significant reductions in all 6 criteria pollutants and reductions are expected to continue.

39 The 1990 Clean Air Act Under this law, EPA sets limits on how much of a pollutant can be in the air anywhere in the United States. This ensures that all Americans have the same basic health and environmental protections. The law allows individual states to have stronger pollution controls, but states are not allowed to have weaker pollution controls than those set for the whole country.

40 Chapter 19: Global Warming and Ozone Loss

41 The Greenhouse effect In the Greenhouse effect, certain gases in the atmosphere trap heat in the troposphere (lower atmosphere). If the atmospheric concentrations of these gases rise and arent removed by other processes, the average temp of the lower atmosphere will gradually increase.

42 Greenhouse gases The major greenhouse gases are water vapor (H20), carbon dioxide (C20), ozone (o3), methane (CH4), nitrous oxide (N2O), and chlorofluorocarbons (CFCs), and a recently identified perfluorocarbons (PFCs) These gases remain in the atmosphere for 2,000-50,000 years. The two predominant gases are water vapor (hyrologic cycle) and carbon dioxide (global carbon cycle)

43 Global warming Measured atmospheric levels of certain greenhouse gases have risen substantially in recent decades and are projected to enhance the earth’s natural greenhouse effect, a phenomenon called global warming Most of the increased levels of these greenhouse gases since 1958 have been caused by human activities such as burning fossil fuels, agricultue, deforestation, and use of CFCs.

44 Carbon dioxide (CO2): Responsible for 50-60% of the global warming from greenhouse gases produced by human activites Main sources are fossil fuel burning (70-75%) and land clearing and burning (20-25%) Remains in atmosphere for years

45 Chloroflurocarbons (CFCs):
Contribute to global warming in the troposphere and also deplete ozone in the stratosphere Main sources are leaking ACs and fridges, evaporation of industrial solvents, production of plastic foams, and aerosol propellants Trap 1,500- 7,000 times as much heat per molecule as CO2 while they are in the troposphere.

46 Methane (CH4): Accounts for about 20% of the overall warming effect
Produced when anaerobic bacteria break down dead organic matter in moist places that lack oxygen. Stays in the troposphere for 9-15 years Each CH4 molecule traps 20 times as much heat as a CO2 molecule

47 Nitrous oxide (N2O): Can trap heat in the troposphere and also deplete ozone in the stratosphere Released from nylon production, burning of biomass and nitrogen-rich fuels, smog-fighting catalytic converters on motor vehicles, and the breakdown of nitrogen fertilizers in soil, livestock wastes, and nitrate-contaminated groundwater. Stays in the troposphere about 120 years. About 200 times as much heat per molecule as CO2

48 According to EPA, emission of greenhouse gases by the US rose by 20% between 1990 and Energy related activities accounted for about 86% of these emissions in 1996, mostly through burning fossil fuels. The atmospheric concentrations of CO2 and other greenhouse gases are projected to double from preindustrial levels sometimes during the next century and then continue to rise

49 The Earth’s past temperatures
Since 1860, mean global temperature after correcting for excess heating over urban areas has risen degrees Celsius. Temperature rose about 0.3 degrees between 1846 and 1997 Since 1860, the thirteen warmest years occurred between 1979 and 1998, with 1990, 1995, 1997, and 1998 being the four hottest years.

50 Future global warming and its effects
According to the latest climate models, the earth’s mean surface temperature should rise degrees celsius between 1990 and 2100. Model projects that once the climate changes, it will continue for hundreds of years. According to the models, the northern hemisphere should warm more and faster than the southern hemisphere because the latter has more heat- absorbing ocean than land and because water cools more slowly than land.


52 How Earth’s climate is affected by various factors
Solar output: ups and downs in solar output can temporarily warm or cool the earth and thus affect the projections of climate models. Two studies showed that the projected warming power of greenhouse gases should outweigh the climatic influence of the sun over at least the next 50 years.

53 Oceans: the oceans might amplify global warming by releasing more CO2 into the atmosphere or might dampen it by absorbing more heat. The oceans currently help moderate tropospheric temperature by removing about 29% of the excess CO2 pumped into the atmosphere

54 Water vapor content and clouds: changes in the atmosphere’s water vapor content and the amount and types of cloud cover also affect climate. Warmer temperatures would increase evaporation and the water-holding capacity of the air and create more clouds. Significant increase in the water vapor, a potent greenhouse gas, could enhance warming (positive feedback).

55 Polar ice: the ability of the earth’s surface to reflect light is called its albedo. Because of their albedo, light-colored Greenland and Antarctic ice sheets act like enormous mirrors, reflecting sunlight back into space. If warmer temperatures melted some of this ice and exposed darker ground or ocean, more sunlight would be absorbed and warming would be accelerated.

56 Air pollution: pollutants in the lower troposphere can either warm or cool the air depending on the reflectivity of the underlying surface. It is hypothesized that SO2 and tiny particles in the troposphere attract enough water molecules to form condensation nuclei, which leads to increased cloud formation

57 Some possible effects of a warmer world
Food production: a warmer global climate could increase food production in some areas and lower it in others, depending on crop- growing capacity and climate belts. Water supply: global warming would reduce water supply, shrinking or completely drying up lakes, streams, and aquifers. Forests and biodiversity: global warming would change the makeup and location of many of the worlds forests

58 Continued… Sea levels: in a warmer world, sea levels are expected to rise, primarily because ocean water expands when heated and because some land-based glacial ice will melt Weather extremes: as more heat is retained in the earth’s climate system, more air will move across the earth’s surface. Human health: global warming would bring more heat waves, which would double or triple heat-related deaths among the elderly and people with heart disease; it would also increase suffering from respiratory ailments such as asthma and bronchitis.

59 Solutions: dealing with global warming
Stabilizing the Co2 levels at the currect level would require reducing current global CO2 emissions by 66-83%. Increased use of nuclear power to reduce the amount of CO2 per unit of electricity as coal Using natural gas could help make the 40 to 50 year transition to an age of energy efficiency and renewable energy.

60 Ozone depletion In a band of the stratosphere kms above the earth’s surface, oxygen is continually converted to ozone and back to oxygen by a sequence of reactions initiated by UV radiation from the sun. UV radiation reaching the stratosphere consists of three bands: A, B, and C. The ozone layer blocks out nearly all of the highest- energy and biologically damaging UV-B band. Ozone depletion by certain chlorine- and bromine- containing chemicals emitted into the atmosphere by human activities is a serious long-term threat to human health, animal life, and the sunlight drive promary producers that support the earth’s food chains.

61 CFCs released into the air rise slowly into the stratosphere
CFCs released into the air rise slowly into the stratosphere. There, under the influence of high energy UV radiation, they break down and release highly reactive chlorine atoms, which speed up the breakdown of highly reactive ozone into O2 and O. This causes ozone to be destroyed faster than it is formed.

62 Solutions: protecting the ozone layer
It will take another years for the ozone layer to return to 1975 levels and another years to return to pre recovery levels. Substitutes are already available for most uses of CFCs. Hydochlorofluorocarbons (HCFCs) contain fewer chlorine atoms per molecule than CFCs Because of their shorter lifetimes in the stratosphere, these compounds should have only about 2.5% of the ozone depleting potential of CFCs.

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