1. Chapter 17: Air Pollution

2. Overview Air Pollution in the Lower Atmosphere Air Pollution in the Lower Atmosphere Controlling Common Pollutants of the Lower Atmosphere Controlling Common Pollutants of the Lower Atmosphere High Altitude Ozone Depletion High Altitude Ozone Depletion Indoor Air Pollution Indoor Air Pollution Controlling Indoor Air Pollution Controlling Indoor Air Pollution

3. Air Pollution in Lower Atmosphere A brief history A brief history The atmosphere has long been a sink for waste disposal The atmosphere has long been a sink for waste disposal Long history of recognition of the existence of atmospheric pollutants Long history of recognition of the existence of atmospheric pollutants Natural photochemical smog recognized in 1550 Natural photochemical smog recognized in 1550 Acid rain first described in 17 th century Acid rain first described in 17 th century Word smog introduced in 1905 Word smog introduced in 1905 Mixture of smoke and fog Mixture of smoke and fog

4. Air Pollution in Lower Atmosphere Two categories Two categories 1. Stationary sources - those that have a relatively fixed location Point sources Point sources emit pollutants from controllable sites emit pollutants from controllable sites Fugitive sources Fugitive sources generate air pollutants from open areas exposed to wind processes generate air pollutants from open areas exposed to wind processes Area sources Area sources well defined areas within which are several sources of air pollutants well defined areas within which are several sources of air pollutants

5. Point source Examples of Stationary Sources Fugitive source

6. Air Pollution in Lower Atmosphere 2. Mobile source - move from place to place while emitting pollutants Automobiles, trucks, buses, aircraft, ships, and trains. Automobiles, trucks, buses, aircraft, ships, and trains.

7. General Effects of Air Pollution Affects many aspects of our environment Affects many aspects of our environment Visual qualities Visual qualities Vegetation Vegetation Animals Animals Soil Soil Water quality Water quality Natural and artificial structures Natural and artificial structures Human health Human health

8. General Effects of Air Pollution Significant factor in human death rate for many large cities Significant factor in human death rate for many large cities Athens, Greece Athens, Greece Number of deaths higher on bad air quality days Number of deaths higher on bad air quality days Hungary Hungary 1 in 17 deaths contributed to air pollution 1 in 17 deaths contributed to air pollution US US 300,000 deaths/year, health cost $50 billion 300,000 deaths/year, health cost $50 billion China China Large cities have major air pollution issues; health cost $50–$100 billion Large cities have major air pollution issues; health cost $50–$100 billion

9. General Effects of Air Pollution Affect human health in several ways Affect human health in several ways Toxic poisoning, cancer, birth defects, eye irritation, and irritation of respiratory system Toxic poisoning, cancer, birth defects, eye irritation, and irritation of respiratory system Increased susceptibility to viral infections, causing pneumonia and bronchitis Increased susceptibility to viral infections, causing pneumonia and bronchitis Increased susceptibility to heart disease Increased susceptibility to heart disease Aggravation of chronic diseases, such as asthma and emphysema Aggravation of chronic diseases, such as asthma and emphysema

10. General Effects of Air Pollution Many air pollutants have synergistic effects Many air pollutants have synergistic effects Do greater damage to the lungs than a combination of the two pollutants would be expected to do based on their separate effects Do greater damage to the lungs than a combination of the two pollutants would be expected to do based on their separate effects

12. Air Pollutants 200 air pollutants recognized and assessed by US EP and listed in Clean Water Act 200 air pollutants recognized and assessed by US EP and listed in Clean Water Act Primary pollutants Primary pollutants Emitted directly into the air Emitted directly into the air Carbon monoxide (58%), volatile organic compounds (11%), nitrogen oxides (15%), sulfur oxides (13%), and particulates (3%) Carbon monoxide (58%), volatile organic compounds (11%), nitrogen oxides (15%), sulfur oxides (13%), and particulates (3%) Secondary pollutants Secondary pollutants Produced through reactions between primary pollutants and normal atmospheric compounds Produced through reactions between primary pollutants and normal atmospheric compounds

14. Primary and Secondary Pollutants Natural pollutant exceed anthropogenic pollutants (other than sulfur and nitrogen oxides) Natural pollutant exceed anthropogenic pollutants (other than sulfur and nitrogen oxides) Release of sulfur dioxide from volcanic eruptions. Release of sulfur dioxide from volcanic eruptions. Release of hydrogen sulfide Release of hydrogen sulfide Geysers and hot springs Geysers and hot springs Biological decay in bogs and marshes Biological decay in bogs and marshes Release of ozone in the lower atmosphere as a result of unstable meteorological conditions Release of ozone in the lower atmosphere as a result of unstable meteorological conditions Emission of particles from wildfires and windstorms Emission of particles from wildfires and windstorms Natural hydrocarbon seeps Natural hydrocarbon seeps

15. Criteria Pollutants There are six criteria pollutants There are six criteria pollutants Sulfur dioxide Sulfur dioxide Nitrogen oxides Nitrogen oxides Carbon monoxide Carbon monoxide Ozone Ozone Particulates Particulates Lead Lead

17. Sulfur Dioxide SO 2 SO 2 Colorless odorless gas Colorless odorless gas Once emitted can be converted to sulfate Once emitted can be converted to sulfate Removed from atmosphere by wet or dry deposition Removed from atmosphere by wet or dry deposition Major human sources: Major human sources: coal power plants coal power plants industrial processes industrial processes

18. Sulfur Dioxide Adverse effects depend on dose and concentration Adverse effects depend on dose and concentration Injury or death to animals and plants Injury or death to animals and plants Corrosion of paint and metals Corrosion of paint and metals Important precursor to acid rain Important precursor to acid rain

19. Nitrogen Oxides Occur in many forms in the atmosphere but largely emitted in two forms: Occur in many forms in the atmosphere but largely emitted in two forms: Nitric oxide - NO Nitric oxide - NO Nitrogen dioxide - NO 2 Nitrogen dioxide - NO 2 A yellow-brown to reddish-brown gas A yellow-brown to reddish-brown gas May be converted to NO 3 2- May be converted to NO 3 2- Both subject to emissions regulation and contribute to smog Both subject to emissions regulation and contribute to smog NO 2 major contributor to acid rain NO 2 major contributor to acid rain

20. Nitrogen Oxides Nearly all NO 2 emitted from human sources Nearly all NO 2 emitted from human sources Combustion of fossil fuels Combustion of fossil fuels Environmental effects Environmental effects Irritate eyes and mucous membranes Irritate eyes and mucous membranes Suppress plant growth Suppress plant growth However, when convert to nitrate may promote plant growth However, when convert to nitrate may promote plant growth

21. Carbon Monoxide CO is a colorless, odorless gas CO is a colorless, odorless gas Even at low concentrations is extremely toxic to humans Even at low concentrations is extremely toxic to humans Binds to hemoglobin in blood Binds to hemoglobin in blood 90% of CO in atmosphere comes from natural sources 90% of CO in atmosphere comes from natural sources 10% comes from fires, cars, and incomplete burning of organic compounds 10% comes from fires, cars, and incomplete burning of organic compounds

22. Ozone and Other Photochemical Oxidants Photochemical oxidants result from atmospheric interactions of nitrogen dioxide and sunlight Photochemical oxidants result from atmospheric interactions of nitrogen dioxide and sunlight Most common is ozone - O 3 Most common is ozone - O 3 Colorless gas with slightly sweet odor Colorless gas with slightly sweet odor Very active chemically, oxidizes or burns Very active chemically, oxidizes or burns Beneficial in the upper atmosphere Beneficial in the upper atmosphere

23. Ozone and Other Photochemical Oxidants Because ozone is a secondary pollutant it is difficult to regulate. Because ozone is a secondary pollutant it is difficult to regulate. Health standards often exceeded in urban areas Health standards often exceeded in urban areas Effects include Effects include Kills leaf tissue at high concentration Kills leaf tissue at high concentration Damage eyes and respiratory system Damage eyes and respiratory system Even young, healthy people may have breathing difficulty on polluted days Even young, healthy people may have breathing difficulty on polluted days

24. Particulate Matter PM10 is made up of particles less than 10μm in diameter PM10 is made up of particles less than 10μm in diameter Present everywhere but high concentrations and/or specific types dangerous Present everywhere but high concentrations and/or specific types dangerous Much particulate matter easily visible as smoke, soot, or dust Much particulate matter easily visible as smoke, soot, or dust Includes airborne asbestos and heavy metals Includes airborne asbestos and heavy metals

25. Particulate Matter Very fine pollutants - greatest concern Very fine pollutants - greatest concern PM 2.5 - less than 2.5 μ m in diameter PM 2.5 - less than 2.5 μ m in diameter Easily inhaled into the lungs, then absorbed into the bloodstream Easily inhaled into the lungs, then absorbed into the bloodstream Ultrafine particles- <0.18 μ m released by automobiles Ultrafine particles- <0.18 μ m released by automobiles Often referred to as Total Suspended Particles (TSPs) Often referred to as Total Suspended Particles (TSPs) Tend to be highest in large cities in developing countries Tend to be highest in large cities in developing countries

27. Particulate Matter Recent studies estimate that 2 to 9% of human mortality in cites is associated with PM Recent studies estimate that 2 to 9% of human mortality in cites is associated with PM Linked to both lung cancer and bronchitis Linked to both lung cancer and bronchitis Especially hazardous to elderly and those with asthma Especially hazardous to elderly and those with asthma Dust can be deposited on plants Dust can be deposited on plants Interferes with absorption of CO 2 and O 2 and transpiration Interferes with absorption of CO 2 and O 2 and transpiration

28. Particulate Matter Block sunlight and may cause climate change Block sunlight and may cause climate change Global dimming Global dimming Gradual reduction in the solar energy that reaches the surface of Earth Gradual reduction in the solar energy that reaches the surface of Earth Cools the atmosphere Cools the atmosphere Lessens global warming Lessens global warming

29. Lead Lead is constituent of auto batteries and was once added to gasoline Lead is constituent of auto batteries and was once added to gasoline Lead in gas emitted into air with exhaust Lead in gas emitted into air with exhaust Spread widely around world in soils and water along roadways Spread widely around world in soils and water along roadways Once in soil can enter the food chain Once in soil can enter the food chain Lead now removed from gas in US, CAN, EU Lead now removed from gas in US, CAN, EU 98% reduction in emissions since 1970s 98% reduction in emissions since 1970s

30. Air Toxics Known/suspected to cause cancer or other serious health problems. Known/suspected to cause cancer or other serious health problems. Associated with long-term and short-term exposures Associated with long-term and short-term exposures Gases, metals, and organic chemicals that are emitted in relatively small volumes Gases, metals, and organic chemicals that are emitted in relatively small volumes Cause respiratory, neurological, reproductive, or immune diseases Cause respiratory, neurological, reproductive, or immune diseases

31. Air Toxics Standards have been set for more than 150 air toxics Standards have been set for more than 150 air toxics Ex: hydrogen sulfide, hydrogen fluoride, chlorine gases, benzene, methanol, ammonia Ex: hydrogen sulfide, hydrogen fluoride, chlorine gases, benzene, methanol, ammonia EPA estimates that the average risk for cancer from exposure to air toxics is about 1 in 21,000 EPA estimates that the average risk for cancer from exposure to air toxics is about 1 in 21,000

32. Hydrogen sulfide Highly toxic corrosive gas easily identified by its rotten egg odor Highly toxic corrosive gas easily identified by its rotten egg odor Produced from Produced from Natural sources such as geysers, swamps, and bogs Natural sources such as geysers, swamps, and bogs Human sources such as industrial plants that produce petroleum or that smelt metals Human sources such as industrial plants that produce petroleum or that smelt metals Effects of hydrogen sulfide Effects of hydrogen sulfide Functional damage to plants Functional damage to plants Range from toxicity to death Range from toxicity to death

33. Hydrogen Fluoride Extremely toxic gaseous pollutant Extremely toxic gaseous pollutant Released by some industrial activities Released by some industrial activities Such as production of aluminum, coal gasification, and burning of coal in power plants Such as production of aluminum, coal gasification, and burning of coal in power plants Even a small concentration (as low as 1 ppb) of HF may cause harm Even a small concentration (as low as 1 ppb) of HF may cause harm Could be bad for grazing animals - forage plants can become toxic when exposed to this gas Could be bad for grazing animals - forage plants can become toxic when exposed to this gas

34. Methyl Isocyanate An ingredient of a common pesticide, Sevin An ingredient of a common pesticide, Sevin Colorless gas Colorless gas Causes severe irritation (burns on contact) to eyes, nose, throat, and lungs Causes severe irritation (burns on contact) to eyes, nose, throat, and lungs If inhaled- violent coughing, swelling of the lungs, bleeding, and death If inhaled- violent coughing, swelling of the lungs, bleeding, and death Lower exposure can cause a variety of problems, including loss of sight Lower exposure can cause a variety of problems, including loss of sight

35. Volatile Organic Compounds (VOC) Variety of organic compounds used as solvents in industrial processes Variety of organic compounds used as solvents in industrial processes Dry cleaning, degreasing, and graphic arts Dry cleaning, degreasing, and graphic arts Hydrocarbons Hydrocarbons Comprise one group of VOCs Comprise one group of VOCs Thousands of hydrocarbon compounds exist, including natural gas, or methane (CH 4 ); butane (C 4 H 10 ); and propane (C 3 H 8 ) Thousands of hydrocarbon compounds exist, including natural gas, or methane (CH 4 ); butane (C 4 H 10 ); and propane (C 3 H 8 )

36. Volatile Organic Compounds Some VOCs react w/ sunlight to produce photochemical smog Some VOCs react w/ sunlight to produce photochemical smog Globally 15% of hydrocarbons emissions are anthropogenic Globally 15% of hydrocarbons emissions are anthropogenic In the US - 50% In the US - 50% Primary human source automobiles Primary human source automobiles

37. Benzene Additive in gasoline and an important industrial solvent Additive in gasoline and an important industrial solvent Produced during incomplete combustion Produced during incomplete combustion Also component of cigarette smoke Also component of cigarette smoke Major environmental source on and off road vehicles Major environmental source on and off road vehicles

38. Arcolein A volatile hydrocarbon that is extremely irritating to nose, eyes, and respiratory system A volatile hydrocarbon that is extremely irritating to nose, eyes, and respiratory system Produced from Produced from Manufacturing processes that involve combustion of petroleum fuels Manufacturing processes that involve combustion of petroleum fuels Component of cigarette smoke Component of cigarette smoke

39. Variability of Air Pollution Problems vary in different regions of the country and the world Problems vary in different regions of the country and the world LA pollution mainly from mobile sources LA pollution mainly from mobile sources Ohio and Great Lakes from point sources Ohio and Great Lakes from point sources Also varies seasonally Also varies seasonally Smog a problem in summer when there greater sunshine Smog a problem in summer when there greater sunshine Particulates a problem in dry months Particulates a problem in dry months

40. Las Vegas: Particulates Particulates a problem in arid regions Particulates a problem in arid regions Little vegetation is present - wind can easily pick up and transport fine dust Little vegetation is present - wind can easily pick up and transport fine dust Brown haze over Las Vegas partly due to naturally occurring PM 10 Brown haze over Las Vegas partly due to naturally occurring PM 10 60% of the dust comes from new construction sites, dirt roads, and vacant land 60% of the dust comes from new construction sites, dirt roads, and vacant land

41. Haze From Afar Air quality concerns are not restricted to urban areas Air quality concerns are not restricted to urban areas North slope of Alaska has an air pollution problem that travel over on the jet stream from Eurasia North slope of Alaska has an air pollution problem that travel over on the jet stream from Eurasia Significant to understanding global air pollution Significant to understanding global air pollution

42. Urban Air Pollution Smog Smog Term first used in 1905 as mixture of smoke and fog that produced unhealthy air Term first used in 1905 as mixture of smoke and fog that produced unhealthy air Two major types Two major types Photochemical smog (LA type smog or brown air) Photochemical smog (LA type smog or brown air) Directly related to automobile use Directly related to automobile use Sulfurous smog (London type smog, gray air, or industrial smog) Sulfurous smog (London type smog, gray air, or industrial smog) Produced by combustion of coal or oil Produced by combustion of coal or oil

45. Urban Air Pollution Whether air pollution develops depends on topography and meteorological conditions Whether air pollution develops depends on topography and meteorological conditions Determine whether air pollution is a nuisance or major health problem Determine whether air pollution is a nuisance or major health problem Primary adverse effect Primary adverse effect Damage to green plants and aggravation of chronic disease Damage to green plants and aggravation of chronic disease Usually low-level over long period of time Usually low-level over long period of time However major disaster have occurred However major disaster have occurred

46. Urban Air Pollution In the lower atmosphere, restricted circulation associated with inversion layers may lead to pollution event In the lower atmosphere, restricted circulation associated with inversion layers may lead to pollution event Atmospheric inversion Atmospheric inversion Occurs when warmer air is found above cooler air Occurs when warmer air is found above cooler air

47. Occurs primarily in summer and fall Occurs when cloud cover associated with stagnant air

48. Urban Air Pollution Cities situated in a valley or topographic bowl are more susceptible to smog problems Cities situated in a valley or topographic bowl are more susceptible to smog problems Surrounding mountains and inversions prevent pollutants from being transported by wind or weather systems Surrounding mountains and inversions prevent pollutants from being transported by wind or weather systems Ex: Los Angeles Ex: Los Angeles

50. Potential for Urban Air Pollution Determined by the following factors: Determined by the following factors: 1. Rate of emission of pollutants per unit area 2. Downwind distance that a mass of air moves through an urban area 3. Average speed of the wind 4. Elevation to which potential pollutants can be thoroughly mixed by naturally moving air in the lower atmosphere

51. Urban Air Pollution Concentration of pollutants in the air is directly proportional to the first two factors Concentration of pollutants in the air is directly proportional to the first two factors As either emission rate or down wind travel distance increase, so will the concentration of pollutants As either emission rate or down wind travel distance increase, so will the concentration of pollutants City air pollution decreases with increases in third and forth factors City air pollution decreases with increases in third and forth factors The stronger the wind and the higher the mixing layer, the lower the pollution The stronger the wind and the higher the mixing layer, the lower the pollution

53. Future Trends for Urban Areas The optimistic view The optimistic view Air quality will continue to improve Air quality will continue to improve We will developed effective ways to reduce pollutants We will developed effective ways to reduce pollutants The pessimistic view The pessimistic view Population pressures and economics will dictate what happens in many parts of the world Population pressures and economics will dictate what happens in many parts of the world The result will be poorer air quality in many locations The result will be poorer air quality in many locations

54. Future Trends for Urban Areas; The United States LA is a good area to look at for strategies for pollution abatement. LA is a good area to look at for strategies for pollution abatement. Air quality plan involving the entire urban region includes the following features: Air quality plan involving the entire urban region includes the following features: Strategies to discourage automobile use and reduce the number of cars. Strategies to discourage automobile use and reduce the number of cars. Stricter emission controls for automobiles Stricter emission controls for automobiles

55. Future Trends for Urban Areas; Developing Countries Don’t have the financial base necessary to fight air pollution Don’t have the financial base necessary to fight air pollution Ex: Mexico City Ex: Mexico City 25 million people 25 million people 50,000 buses, millions of cars 50,000 buses, millions of cars Topographically located in a natural basin Topographically located in a natural basin Perfect situation for severe air pollution problem Perfect situation for severe air pollution problem

56. Controlling Common Pollutants The most reasonable strategies: The most reasonable strategies: Reduce Reduce Collect Collect Capture Capture Retain Retain Reduction of emissions through energy efficiency and conservation measures is preferred Reduction of emissions through energy efficiency and conservation measures is preferred

57. Pollution Control: Particulates Particulates emitted from fugitive, point or area stationary sources are much easier to control Particulates emitted from fugitive, point or area stationary sources are much easier to control Point/area sources can be controlled by Point/area sources can be controlled by Settling chambers or collectors which cause particulates to settle out Settling chambers or collectors which cause particulates to settle out Fugitive sources controlled by Fugitive sources controlled by Protecting open areas Protecting open areas Controlling dust Controlling dust Reducing effects of wind Reducing effects of wind

58. Pollution Control: Automobiles Pollution control in automobiles Pollution control in automobiles Carbon monoxide and Hydrocarbon emissions- Catalytic converter Carbon monoxide and Hydrocarbon emissions- Catalytic converter Nitrogen oxides emissions- Recirculating exhaust gas Nitrogen oxides emissions- Recirculating exhaust gas Automobile emission regulations plan in US has not been effective Automobile emission regulations plan in US has not been effective Pollutants may be low when car is new Pollutants may be low when car is new Many people do not maintain them properly Many people do not maintain them properly Strategies Strategies Effluent fees replace emission controls Effluent fees replace emission controls Reduce the number or type of cars Reduce the number or type of cars

59. Pollution Control: Sulfur Dioxide Can be reduced through abatement measures performed before, during, or after combustion Can be reduced through abatement measures performed before, during, or after combustion Cleaner coal technology available Cleaner coal technology available Makes fuel more expensive Makes fuel more expensive Switch to low-sulfur coal Switch to low-sulfur coal Transportation is an issue Transportation is an issue

60. Pollution Control: Sulfur Dioxide Washing it to remove sulfur Washing it to remove sulfur Iron sulfide settles out Iron sulfide settles out Ineffective for removing organic sulfur Ineffective for removing organic sulfur Coal gasification Coal gasification Converts coal to gas in order to remove sulfur Converts coal to gas in order to remove sulfur Gas obtained is clean Gas obtained is clean

61. Pollution Control: Sulfur Dioxide Emissions from power plants can be reduced by removing the oxides from the gases in the stack - Scrubbing Emissions from power plants can be reduced by removing the oxides from the gases in the stack - Scrubbing Flue gas desulfurization Flue gas desulfurization Occurs after coal is burned Occurs after coal is burned Gases treated with slurry of lime or limestone Gases treated with slurry of lime or limestone Reacts to form calcium sulfite Reacts to form calcium sulfite Can be process into building materials Can be process into building materials

63. Clean Air Act Amendments of 1990 Regulations enacted by the U.S. Congress that address Regulations enacted by the U.S. Congress that address Acid rain Acid rain Toxic emissions Toxic emissions Ozone depletion Ozone depletion Automobile exhaust Automobile exhaust Buying and selling of sulfur dioxide emissions Buying and selling of sulfur dioxide emissions Nitrogen dioxides- reduced by 10 million tons Nitrogen dioxides- reduced by 10 million tons Toxins- especially those causing cancer Toxins- especially those causing cancer

64. Ambient Air Quality Standards Tied to emission standards that attempt to control air pollution Tied to emission standards that attempt to control air pollution Tougher standards set for ozone and PM 2.5 Tougher standards set for ozone and PM 2.5

65. Air Quality Index Used to describe air pollution on a given day Used to describe air pollution on a given day Determined from measurements of the concentration of five major pollutants: Determined from measurements of the concentration of five major pollutants: Particulate matter, sulfur dioxide, carbon monoxide, ozone, and nitrogen dioxide. Particulate matter, sulfur dioxide, carbon monoxide, ozone, and nitrogen dioxide.

66. Air Quality Index AQI = 100 AQI = 100 Air is unhealthy Air is unhealthy AQI greater than 200 AQI greater than 200 Air pollution alert is issued Air pollution alert is issued AQI exceeds 300 AQI exceeds 300 Air pollution warning is issued - hazardous to all people. Air pollution warning is issued - hazardous to all people. AQI exceeds 400 AQI exceeds 400 Air pollution emergency is declared, and people are requested to remain indoors and minimize physical exertion Air pollution emergency is declared, and people are requested to remain indoors and minimize physical exertion

68. Cost of Outdoor Air Pollution Control Fossil fuel-burning pollution control Fossil fuel-burning pollution control A few hundred dollars per additional ton of particulates removed A few hundred dollars per additional ton of particulates removed Aluminum plant Aluminum plant May be several thousand per ton May be several thousand per ton Cost benefit must be considered Cost benefit must be considered

69. Cost of Outdoor Air Pollution Control Economic analysis of air pollution includes many variables, some of which are hard to quantify Economic analysis of air pollution includes many variables, some of which are hard to quantify We do know the following: We do know the following: With increasing air pollution controls, the capital cost for technology to control air pollution increases With increasing air pollution controls, the capital cost for technology to control air pollution increases As the controls for air pollution increase, the loss from pollution damages decreases As the controls for air pollution increase, the loss from pollution damages decreases The total cost of air pollution is the cost of pollution control plus the environmental damages of the pollution The total cost of air pollution is the cost of pollution control plus the environmental damages of the pollution

70. Ozone Depletion Ozone (O 3 ) Ozone (O 3 ) Triatomic form of oxygen in which three atoms of oxygen are bonded Triatomic form of oxygen in which three atoms of oxygen are bonded Strong oxidant and chemically reacts with many materials in the atmosphere Strong oxidant and chemically reacts with many materials in the atmosphere In the lower atmosphere, ozone is a pollutant In the lower atmosphere, ozone is a pollutant Highest concentration of ozone in the stratosphere Highest concentration of ozone in the stratosphere

72. Ultraviolet Radiation and Ozone Ozone layer in the stratosphere called the ozone shield Ozone layer in the stratosphere called the ozone shield Absorbs most of the potentially hazardous ultraviolet radiation from the sun Absorbs most of the potentially hazardous ultraviolet radiation from the sun Ultraviolet radiation consists of wavelengths between 0.1 and 0.4 μm Ultraviolet radiation consists of wavelengths between 0.1 and 0.4 μm Ultraviolet A (UVA) Ultraviolet A (UVA) Ultraviolet B (UVB) Ultraviolet B (UVB) Ultraviolet C (UVC). Ultraviolet C (UVC).

74. Ultraviolet Radiation and Ozone Ultraviolet C (UVC) Ultraviolet C (UVC) Shortest wavelength and most energetic of the types of ultraviolet radiation Shortest wavelength and most energetic of the types of ultraviolet radiation Sufficient energy to break apart diatomic oxygen (O 2 ) Sufficient energy to break apart diatomic oxygen (O 2 ) Each of these oxygen atoms may combine with an O 2 molecule to create ozone Each of these oxygen atoms may combine with an O 2 molecule to create ozone UVC strongly absorbed in the stratosphere, and negligible amounts reach the Earth’s surface UVC strongly absorbed in the stratosphere, and negligible amounts reach the Earth’s surface

75. Ultraviolet Radiation and Ozone Ultraviolet A (UVA) Ultraviolet A (UVA) Longest wavelength Longest wavelength Least energy of the three types of ultraviolet radiation Least energy of the three types of ultraviolet radiation UVA can cause some damage to living cells UVA can cause some damage to living cells Not affected by stratospheric ozone, and is transmitted to the Earth’s surface Not affected by stratospheric ozone, and is transmitted to the Earth’s surface

76. Ultraviolet Radiation and Ozone Ultraviolet B (UVB) Ultraviolet B (UVB) Energetic and strongly absorbed by stratospheric ozone Energetic and strongly absorbed by stratospheric ozone Ozone is the only known gas that absorbs UVB Ozone is the only known gas that absorbs UVB Depletion of ozone in the stratosphere results in an increase in the UVB that reaches the surface of the Earth Depletion of ozone in the stratosphere results in an increase in the UVB that reaches the surface of the Earth

77. Ultraviolet Radiation and Ozone Approximately 99% of all ultraviolet solar radiation (all UVC and most UVB) is absorbed by the ozone layer Approximately 99% of all ultraviolet solar radiation (all UVC and most UVB) is absorbed by the ozone layer Natural service function Natural service function Protects us from the potentially harmful effects of ultraviolet radiation Protects us from the potentially harmful effects of ultraviolet radiation

78. Measurement of Stratospheric Ozone First measured in 1920s using Dobson ultraviolet spectrometer. First measured in 1920s using Dobson ultraviolet spectrometer. Dobson unit (DU) - 1DU = 1 ppb O 3 Dobson unit (DU) - 1DU = 1 ppb O 3 Now have measurements from all over the world for 30 years Now have measurements from all over the world for 30 years Ground based measurements first identified ozone depletion over the Antarctic Ground based measurements first identified ozone depletion over the Antarctic Concentrations have been decreasing since the mid- 1970s Concentrations have been decreasing since the mid- 1970s “Ozone hole” “Ozone hole”

79. Ozone Depletion and CFCs Hypothesis that ozone in the stratosphere is being depleted by CFCs Hypothesis that ozone in the stratosphere is being depleted by CFCs Based on physical and chemical properties of CFCs and knowledge about atmospheric conditions Based on physical and chemical properties of CFCs and knowledge about atmospheric conditions Vigorously debated by scientists, companies producing CFCs, and other interested parties Vigorously debated by scientists, companies producing CFCs, and other interested parties

80. Ozone Depletion and CFCs The major features of the hypothesis: The major features of the hypothesis: CFCs emitted in the lower atmosphere are extremely stable and therefore have a very long residence time (about 100 years) CFCs emitted in the lower atmosphere are extremely stable and therefore have a very long residence time (about 100 years) CFCs eventually wander upward and enter the stratosphere CFCs eventually wander upward and enter the stratosphere Once above the stratospheric ozone, they may be destroyed by UV radiation, releasing chlorine, a highly reactive atom Once above the stratospheric ozone, they may be destroyed by UV radiation, releasing chlorine, a highly reactive atom

81. Ozone Depletion and CFCs The chlorine released then depletes the ozone The chlorine released then depletes the ozone Depletion increases the amount of UVB radiation that reaches Earth’s surface Depletion increases the amount of UVB radiation that reaches Earth’s surface UVB is a cause of human skin cancers and is also thought to be harmful to the human immune system UVB is a cause of human skin cancers and is also thought to be harmful to the human immune system

82. Emissions and Uses of Ozone Depleting Chemicals CFCs have been used CFCs have been used As aerosol propellants in spray cans As aerosol propellants in spray cans Working gas in refrigeration and AC Working gas in refrigeration and AC Production of Styrofoam Production of Styrofoam No longer used in spray cans but use has increased in refrigerants No longer used in spray cans but use has increased in refrigerants

83. Simplified Stratospheric Chlorine Chemistry CFCs are CFCs are transparent to sunlight, transparent to sunlight, essentially insoluble essentially insoluble Non-reactive in the oxygen-rich lower atmosphere Non-reactive in the oxygen-rich lower atmosphere When CFCs reach the stratosphere, reactions do occur When CFCs reach the stratosphere, reactions do occur UVC splits up the CFC releasing chlorine, the following two reactions can take place: UVC splits up the CFC releasing chlorine, the following two reactions can take place: Cl + O3 → ClO + O2 ClO + O → Cl + O2

84. Simplified Stratospheric Chlorine Chemistry This series of reactions is what is known as a catalytic chain reaction This series of reactions is what is known as a catalytic chain reaction Chlorine is not removed Chlorine is not removed Reappears in the second reaction Reappears in the second reaction Repeated over and over Repeated over and over Process considerably more complex Process considerably more complex Chain can be interrupted and Cl stored in other reactions Chain can be interrupted and Cl stored in other reactions

86. The Antarctic Ozone Hole Since 1958 ozone depletion has been observed in the Antarctic every October. Since 1958 ozone depletion has been observed in the Antarctic every October. Thickness decreasing and geographic area increasing Thickness decreasing and geographic area increasing Polar Stratospheric Clouds Polar Stratospheric Clouds Form during the polar winter (polar night) Form during the polar winter (polar night) Air circulates about the pole in Antarctic polar vortex. Air circulates about the pole in Antarctic polar vortex. Forms as the isolated air mass cools, condenses, and descends. Forms as the isolated air mass cools, condenses, and descends.

87. Polar Stratospheric Clouds Type I polar stratospheric clouds Type I polar stratospheric clouds When air mass reach a temp between 195 K and 190 K, small sulfuric acid particles are frozen and serve as seed particles for nitric acid (HNO 3 ). When air mass reach a temp between 195 K and 190 K, small sulfuric acid particles are frozen and serve as seed particles for nitric acid (HNO 3 ). Type II polar stratospheric clouds Type II polar stratospheric clouds If temperatures drop below 190 K water vapor condenses around Type I cloud particles If temperatures drop below 190 K water vapor condenses around Type I cloud particles

88. Polar Stratospheric Clouds During the formation nearly all nitrogen oxides held in clouds During the formation nearly all nitrogen oxides held in clouds Facilitates ozone depleting reactions Facilitates ozone depleting reactions When spring comes and sun returns it breaks apart Cl 2 When spring comes and sun returns it breaks apart Cl 2 Chlorine can not be sequestered to form chlorine nitrate, one of its carbon sinks. Chlorine can not be sequestered to form chlorine nitrate, one of its carbon sinks.

91. An Arctic Ozone Hole? Polar vortex also forms over the North Pole Polar vortex also forms over the North Pole Weaker and does not last as long as Antarctic Weaker and does not last as long as Antarctic Ozone depletion does occur at the NP Ozone depletion does occur at the NP Major concern is ozone-deficient air moving southward over population centers. Major concern is ozone-deficient air moving southward over population centers.

92. Environmental Effects Several serious potential environmental effects Several serious potential environmental effects Damage to food chain on land and in oceans (loss of primary production ) Damage to food chain on land and in oceans (loss of primary production ) Damage to human health (skin cancers, cataracts, and suppression of immune system) Damage to human health (skin cancers, cataracts, and suppression of immune system) UV Index measure of UV radiation on a given day UV Index measure of UV radiation on a given day

94. Environmental Effects Reduce the risk of skin cancer and other skin damage from UV exposure by: Reduce the risk of skin cancer and other skin damage from UV exposure by: Limit exposure to the sun between the hours of 10 A.M.and 4 P.M. Limit exposure to the sun between the hours of 10 A.M.and 4 P.M. Use a sunscreen with an SPF of at least 30 Use a sunscreen with an SPF of at least 30 Wear a wide-brimmed hat and, where possible, tightly woven full-length clothing Wear a wide-brimmed hat and, where possible, tightly woven full-length clothing Wear UV-protective sunglasses Wear UV-protective sunglasses Avoid tanning salons and sunlamps Avoid tanning salons and sunlamps Consult the UV Index before going out Consult the UV Index before going out

95. Future of Ozone Depletion The Montreal Protocol The Montreal Protocol Outlined a plan for the eventual reduction of global emissions of CFCs to 50% of 1986 emissions Outlined a plan for the eventual reduction of global emissions of CFCs to 50% of 1986 emissions Elimination of the production of CFCs by 1999 Elimination of the production of CFCs by 1999 Assessment of the protocol suggest that CFCs will return to pre-1980 levels by 2050 Assessment of the protocol suggest that CFCs will return to pre-1980 levels by 2050

96. Future of Ozone Depletion Substitutes for CFCs Substitutes for CFCs Hydrofluorocarbons (HFCs) Hydrofluorocarbons (HFCs) Do not contain chlorine Do not contain chlorine Fluorine atoms participate in reactions similar to those of chlorine - 1,000 times less efficient in those reactions Fluorine atoms participate in reactions similar to those of chlorine - 1,000 times less efficient in those reactions Hydrochlorofluorocarbons (HCFCs). Hydrochlorofluorocarbons (HCFCs). Contain an atom of hydrogen in place of one chlorine atom Contain an atom of hydrogen in place of one chlorine atom Can be broken down in the lower atmosphere Can be broken down in the lower atmosphere Still causes ozone depletion if they do reach the stratosphere before being broken down Still causes ozone depletion if they do reach the stratosphere before being broken down

97. Sources of Indoor Air Pollution Secondhand smoke Secondhand smoke Most hazardous common indoor air pollutant Most hazardous common indoor air pollutant Legionella pneumophila Legionella pneumophila Bacterium that causes a type of pneumonia called Legionnaires’ disease when inhaled Bacterium that causes a type of pneumonia called Legionnaires’ disease when inhaled Some molds (fungal growths) in buildings release toxic spores Some molds (fungal growths) in buildings release toxic spores Cause chronic inflammation and scarring of lungs Cause chronic inflammation and scarring of lungs

98. Sources of Indoor Air Pollution Radon gas Radon gas Seeps up naturally from soils and rocks below buildings Seeps up naturally from soils and rocks below buildings Thought to be the second most common cause of lung cancer Thought to be the second most common cause of lung cancer Pesticides Pesticides Deliberately or inadvertently applied in buildings to control pest Deliberately or inadvertently applied in buildings to control pest Toxic to people as well Toxic to people as well Some varieties of asbestos Some varieties of asbestos Known to cause a particular type of lung cancer Known to cause a particular type of lung cancer

99. Sources of Indoor Air Pollution Formaldehyde Formaldehyde A VOC, used in many materials found in homes and offices A VOC, used in many materials found in homes and offices Dust mites and pollen Dust mites and pollen Irritate the respiratory system, nose, eyes, and skin of people who are sensitive to them Irritate the respiratory system, nose, eyes, and skin of people who are sensitive to them

102. Sources of Indoor Air Pollution Common indoor air pollutants are often highly concentrated compared with outdoor levels Common indoor air pollutants are often highly concentrated compared with outdoor levels Many potential indoor sources of pollutants. Many potential indoor sources of pollutants. Effectiveness of the steps we have taken to conserve energy in buildings has led to the trapping of pollutants inside Effectiveness of the steps we have taken to conserve energy in buildings has led to the trapping of pollutants inside

104. Pathways, Processes, and Driving Forces Many air pollutants originate within buildings and may be concentrated there because of lack of proper ventilation Many air pollutants originate within buildings and may be concentrated there because of lack of proper ventilation Other air pollutants may enter by infiltration, Other air pollutants may enter by infiltration, Through cracks and other openings in the foundations and walls Through cracks and other openings in the foundations and walls Or by way of ventilation systems Or by way of ventilation systems

105. Pathways, Processes, and Driving Forces Both natural and human processes create differential pressures that move air and contaminants from one area to another Both natural and human processes create differential pressures that move air and contaminants from one area to another Areas of high pressure may develop on the windward side of a building, drawing air in Areas of high pressure may develop on the windward side of a building, drawing air in Pressure is lower on the leeward, or protected, side Pressure is lower on the leeward, or protected, side

106. Pathways, Processes, and Driving Forces A chimney effect (or stack effect) A chimney effect (or stack effect) Occurs when there is a temperature differential between the indoor and outdoor environments Occurs when there is a temperature differential between the indoor and outdoor environments Warmer air rises in the building to the upper levels, it is replaced in the lower portion of the building by outdoor air Warmer air rises in the building to the upper levels, it is replaced in the lower portion of the building by outdoor air Secondhand smoke, may also be drawn into a building by the chimney effect. Secondhand smoke, may also be drawn into a building by the chimney effect.

107. Heating, Ventilation, and Air- Conditioning Systems Systems are designed to provide a comfortable indoor environment for people Systems are designed to provide a comfortable indoor environment for people Design depends on a number of variables Design depends on a number of variables Including the activity of people in the building, air temperature and humidity, and air quality. Including the activity of people in the building, air temperature and humidity, and air quality. If designed correctly, the system will If designed correctly, the system will Provide thermal comfort for people inhabiting the building Provide thermal comfort for people inhabiting the building Provide the necessary ventilation (utilizing outdoor air) Provide the necessary ventilation (utilizing outdoor air) Remove common air pollutants via exhaust fans and filters Remove common air pollutants via exhaust fans and filters

108. Environmental Tobacco Smoke Environmental tobacco smoke (ETS) Environmental tobacco smoke (ETS) Secondhand smoke Secondhand smoke Comes from two sources: Comes from two sources: smoke exhaled by smokers smoke exhaled by smokers smoke emitted from burning tobacco in cigarettes, cigars, or pipes. smoke emitted from burning tobacco in cigarettes, cigars, or pipes. People who are exposed to ETS are referred to as passive smokers. People who are exposed to ETS are referred to as passive smokers.

109. Environmental Tobacco Smoke It is hazardous for the following reasons: It is hazardous for the following reasons: Tobacco smoke contains several thousand chemicals, many of which are irritants. Tobacco smoke contains several thousand chemicals, many of which are irritants. Studies of nonsmoking workers exposed to ETS found that they have reduced airway functions, suffer more illnesses, and lose more work time than those not exposed to ETS Studies of nonsmoking workers exposed to ETS found that they have reduced airway functions, suffer more illnesses, and lose more work time than those not exposed to ETS 3,000 deaths from lung cancer and 40,000 deaths from heart disease a year are thought to be associated with ETS (in US0 3,000 deaths from lung cancer and 40,000 deaths from heart disease a year are thought to be associated with ETS (in US0

110. Radon Gas Radon is a naturally occurring radioactive gas Radon is a naturally occurring radioactive gas Colorless, odorless, and tasteless. Colorless, odorless, and tasteless. Radioactive decay chain from radiogenic uranium to stable lead Radioactive decay chain from radiogenic uranium to stable lead Radon-222 has a half-life of 3.8 days, is the product of radioactive decay of radium-226. Radon-222 has a half-life of 3.8 days, is the product of radioactive decay of radium-226. Radon decays with emission of an alpha particle to polonium-218, which has a half-life of ~ 3 minutes Radon decays with emission of an alpha particle to polonium-218, which has a half-life of ~ 3 minutes

111. Geology and Radon Gas The concentration of radon gas can enter our dwellings depends on concentration of radon in the rocks and soil The concentration of radon gas can enter our dwellings depends on concentration of radon in the rocks and soil Some regions in the United States contain bedrock with an above-average natural concentration of uranium Some regions in the United States contain bedrock with an above-average natural concentration of uranium

112. How Does Radon Gas Enter Building? Three main ways: Three main ways: 1. Migration from soil and rock into basements and lower floors 2. Dissolved in groundwater, it is pumped into wells and then into homes 3. Radon-contaminated materials, such as building blocks, are used in construction

113. Sick Buildings There are two types of sick buildings: There are two types of sick buildings: Buildings with identifiable problems Buildings with identifiable problems Occurrences of toxic molds or bacteria known to cause disease Occurrences of toxic molds or bacteria known to cause disease Diseases are known as building-related illnesses (BRI) Diseases are known as building-related illnesses (BRI) Buildings with sick building syndrome (SBS) Buildings with sick building syndrome (SBS) Symptoms people report cannot be traced to any one known cause Symptoms people report cannot be traced to any one known cause

114. Sick Buildings When the cause is not detected. A number of things may be happening: When the cause is not detected. A number of things may be happening: The complaints result from the combined effects of a number of contaminants present in the building The complaints result from the combined effects of a number of contaminants present in the building Environmental stress from another source is responsible Environmental stress from another source is responsible Employment-related stress may be leading to the symptoms reported Employment-related stress may be leading to the symptoms reported Pollutants or toxins may be present but not identified Pollutants or toxins may be present but not identified

115. Control of Indoor Air Pollution Strong financial incentives to provide workers with a clean air environment Strong financial incentives to provide workers with a clean air environment Meet minimum indoor air quality standards Meet minimum indoor air quality standards Including increase in the inflow of fresh air through ventilation Including increase in the inflow of fresh air through ventilation

116. Control of Indoor Air Pollution One of the principal means for controlling quality is by dilution One of the principal means for controlling quality is by dilution Fresh outdoor air mixed Fresh outdoor air mixed Ventilating air-conditioning system Ventilating air-conditioning system Windows that can be opened Windows that can be opened Various types of air-cleaning systems reduce potential pollutants Various types of air-cleaning systems reduce potential pollutants Particles, vapors, and gases Particles, vapors, and gases Can be installed as part of the heating, ventilation, and AC system or as stand-alone appliances Can be installed as part of the heating, ventilation, and AC system or as stand-alone appliances

117. Control of Indoor Air Pollution Education also plays an important role Education also plays an important role May involve deciding not to install unvented or poorly vented appliances. May involve deciding not to install unvented or poorly vented appliances. Educated people are more aware of their legal rights with respect to product liability and safety. Educated people are more aware of their legal rights with respect to product liability and safety. Education provides people with the information necessary to make decisions concerning exposure, and strategies to avoid potentially hazardous conditions in the home and workplace. Education provides people with the information necessary to make decisions concerning exposure, and strategies to avoid potentially hazardous conditions in the home and workplace.