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Chapter 20: air pollution

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1 Chapter 20: air pollution
Pollution unit

2 20.1 Layers of the Atmosphere

3 Atmospheric pressure (millibars) Altitude (kilometers)
200 400 600 800 1,000 120 75 Highlights: Pressure decreases with altitude until it reaches zero Troposphere is the layer we live in; mostly N and O; weather; colder as you go up Stratosphere: has the ozone layer; warmer as you go up Environmental science focuses mostly on those two layers Temperature 110 Pressure 65 100 Thermosphere 90 55 80 Heating via ozone Mesosphere 45 70 Altitude (kilometers) 60 Altitude (miles) 35 50 Stratosphere 40 25 30 15 Ozone “layer” 20 Heating from the earth Troposphere 10 5 Pressure = 1,000 millibars at ground level (Sea Level) –80 –40 40 80 120 Temperature (˚C)

4 What SPF is that ozone? Stratospheric ozone absorbs 95% of UV radiation 3O UV  2 O3 Tropospheric ozone is harmful to plants, animals, and humans. Tropospheric ozone is made when air pollutants undergo chemical reactions because of UV exposure.

5 Which ozone is which? The oxygen atom generated from the initial reaction reacts with atmospheric, diatomic oxygen, to form ozone. This polluting ozone of the lithosphere, traps heat and contributes to thermal inversion.

6 20.2 Outdoor Air Pollution .

7 Primary & Secondary Pollutants
Play intro video

8 Primary vs. Secondary Primary Pollutants CO CO2 Secondary Pollutants
SO2 NO NO2 SO3 Most hydrocarbons HNO3 H2SO4 Most suspended particles H2O2 O3 PANs SO4 2 Most NO3 and salts Sources Natural Stationary Mobile Primary vs. Secondary

9 Tip – Can’t remember what organic compounds are???
View my PS (Chapter 9) PPT online for a quick refresher.

10 Table 20-1 Page 436 Major classes of air pollutants Class
Carbon oxides Sulfur oxides Nitrogen oxides Volatile organic compounds (VOCs) Suspended particulate matter (SPM) Photochemical oxidants Radioactive substances Hazardous air pollutants (HAPs), which cause health effects such as cancer, birth defects, and nervous system problems Examples Carbon monoxide (CO) and carbon dioxide (CO2) Sulfur dioxide (SO2) and sulfur trioxide (SO3) Nitric oxide (NO), nitrogen dioxide (NO2), nitrous oxide (N2O) (NO and NO2 often are lumped together and labeled NOx) Methane (CH4), propane (C3H8), chlorofluorocarbons (CFCs) Solid particles (dust, soot, asbestos, lead, nitrate, and sulfate salts), liquid droplets (sulfuric acid, PCBs, dioxins, and pesticides) Ozone (O3), peroxyacyl nitrates (PANs), hydrogen peroxide (H2O2), aldehydes Radon-222, iodine-131, strontium-90, plutonium-239 (Table 3-1, p. 49) Carbon tetrachloride (CCl4), methyl chloride (CH3Cl), chloroform (CHCl3), benzene (C6H6), ethylene dibromide (C2H2Br2), formaldehyde (CH2O2) Table 20-1 Page 436

11 Carbon Monoxide CARBON MONOXIDE (CO)
Table 20-2 Major Outdoor Air Pollutants CARBON MONOXIDE (CO) Description: Colorless, odorless gas that is poisonous to air-breathing animals; forms during the incomplete combustion of carbon-containing fuels (2 C + O2 2 CO). Major human sources: Cigarette smoking (p. 409), incomplete burning of fossil fuels. About 77% (95% in cities)comes from motor vehicle exhaust. Health effects: Reacts with hemoglobin in red blood cells and reduces the ability of blood to bring oxygen to body cells and tissues. This impairs perception and thinking; slows reflexes; causes headaches, drowsiness, dizziness, and nausea; can trigger heart attacks and angina; damages the development of fetuses and young children; and aggravates chronic bronchitis, emphysema, and anemia. At high levels it causes collapse, coma, irreversible brain cell damage, and death. Carbon Monoxide

12 Table 20-2 Page 438 Nitrogen Dioxide NITROGEN DIOXIDE (NO2)
Table 20-2 Major Outdoor Air Pollutants Table 20-2 Page 438 NITROGEN DIOXIDE (NO2) Description: Reddish-brown irritating gas that gives photochemical smog its brownish color; in the atmosphere can be converted to nitric acid (HNO3), a major component of acid deposition. Major human sources: Fossil fuel burning in motor vehicles (49%) and power and industrial plants (49%). Health effects: Lung irritation and damage; aggravates asthma and chronic bronchitis; increases susceptibility to respiratory infections such as the flu and common colds (especially in young children and older adults). Environmental effects: Reduces visibility; acid deposition of HNO3 can damage trees, soils, and aquatic life in lakes. Property damage: HNO3 can corrode metals and eat away stone on buildings, statues, and monuments; NO2 can damage fabrics. Nitrogen Dioxide

13 Table 20-2 Page 438 Sulfur Dioxide SULFUR DIOXIDE (SO2)
Table 20-2 Major Outdoor Air Pollutants Table 20-2 Page 438 SULFUR DIOXIDE (SO2) Description: Colorless, irritating; forms mostly from the combustion of sulfur containing fossil fuels such as coal and oil (S + O2 SO2); in the atmosphere can be converted to sulfuric acid (H2SO4), a major component of acid deposition. Major human sources: Coal burning in power plants (88%) and industrial processes (10%). Health effects: Breathing problems for healthy people; restriction of airways in people with asthma; chronic exposure can cause a permanent condition similar to bronchitis. According to the WHO, at least 625 million people are exposed to unsafe levels of sulfur dioxide from fossil fuel burning. Environmental effects: Reduces visibility; acid deposition of H2SO4 can damage trees, soils, and aquatic life in lakes. Property damage: SO2 and H2SO4 can corrode metals and eat away stone on buildings, statues, and monuments; SO2 can damage paint, paper, and leather. Sulfur Dioxide

14 Suspended Particulate Matter
Table 20-2 Major Outdoor Air Pollutants Table 20-2 Page 438 SUSPENDED PARTICULATE MATTER (SPM) Description: Variety of particles and droplets (aerosols) small and light enough to remain suspended in atmosphere for short periods (large particles) to long periods (small particles; Figure 20-6, p. 441); cause smoke, dust, and haze. Major human sources: Burning coal in power and industrial plants (40%), burning diesel and other fuels in vehicles (17%), agriculture (plowing, burning off fields), unpaved roads, construction. Health effects: Nose and throat irritation, lung damage, and bronchitis; aggravates bronchitis and asthma; shortens life; toxic particulates (such as lead, cadmium, PCBs, and dioxins) can cause mutations, reproductive problems, cancer. Environmental effects: Reduces visibility; acid deposition of H2SO4 droplets can damage trees, soils, and aquatic life in lakes. Property damage: Corrodes metal; soils and discolors buildings, clothes, fabrics, and paints. Suspended Particulate Matter

15 Table 20-2 Major Outdoor Air Pollutants
Table 20-2 Page 438 LEAD Description: Solid toxic metal and its compounds, emitted into the atmosphere as particulate matter. Major human sources: Paint (old houses), smelters (metal refineries), lead manufacture, storage batteries, leaded gasoline (being phased out in developed countries). Health effects: Accumulates in the body; brain and other nervous system damage and mental retardation (especially in children); digestive and other health problems; some lead-containing chemicals cause cancer in test animals. Environmental effects: Can harm wildlife. Lead

16 Table 20-2 Page 438 Ozone OZONE (O3)
Table 20-2 Major Outdoor Air Pollutants Table 20-2 Page 438 OZONE (O3) Description: Highly reactive, irritating gas with an unpleasant odor that forms in the troposphere as a major component of photochemical smog (Figures 20-3 and 20-5). Major human sources: Chemical reaction with volatile organic compounds (VOCs, emitted mostly by cars and industries) and nitrogen oxides to form photochemical smog (Figure 20-5). Health effects: Breathing problems; coughing; eye, nose, and throat irritation; aggravates chronic diseases such as asthma, bronchitis, emphysema, and heart disease; reduces resistance to colds and pneumonia; may speed up lung tissue aging. Environmental effects: Ozone can damage plants and trees; smog can reduce visibility. Property damage: Damages rubber, fabrics, and paints. Ozone

17 20.3 Photochemical and Industrial Smog

18 Smog Photochemical: “brown air smog” Caused by UV reacting with chemicals (NOx, VOCs in the atmosphere) Found in modern cities, especially in warm, sunny areas. Industrial smog: “gray air smog” Caused by burning of fossil fuels, adds sulfur to air. Rare in developed countries now as soot is removed by filters..

19 Photochemical Smog Nitrogen oxide is an essential ingredient of photochemical smog that is produced during the high temperatures associated with combustion of vehicle’s engines. Be sure to look at sheet “Chemistry is indeed relevant to APES.”

20 Initial reaction of nitrogen dioxide with sunlight

21 Factors in smog formation
Decrease smog Increase smog Urban buildings Hills and mountains High temperatures “Grasshopper Effect” Precipitation Salty sea spray Wind Reduce factory/car emissions

22 “Grasshopper Effect” This is one reason why the dangerous chemicals Canada banned more than 20 years ago continue to turn up in the Great Lakes.

23 View “Chemistry is indeed relevant to APES.”
See equation – reactants and products of photochemical smog on sheet. Hydrocarbons (including VOC’s), carbon monoxide, and nitrogen oxides from vehicle exhausts are irradiated by sunlight in the presence of oxygen gas. The resulting reactions produce a potentially dangerous mixture that include other NOx, ozone, and irritating organic compounds (VOC’s), as well as CO2 and H2O vapor

24 That’s just smoke out your…….

25 20.4 Regional Outdoor Air Pollution from Acid Deposition

26 Acid Rain Play intro video

27 Chemistry and Acid Rain
The pH of rainwater is normally slightly acidic, at about 5.6, due mainly to reaction of carbon dioxide with water to form carbonic acid. Refer to “Chemistry is indeed relevant to APES.”

28 Gases from natural events
Volcanic eruptions, forest fires, and lightning produce sulfur dioxide, sulfur trioxide, and nitrogen dioxide. These gases can react with atmospheric water in much the same way that carbon dioxide does to produce sulfurous acid, sulfuric acid, nitric acid and nitrous acid. Refer to “Chemistry is indeed relevant to APES.”

29 Acid Rain formation Wind Transformation to sulfuric acid (H2SO4)
and nitric acid (HNO3) Windborne ammonia gas and particles of cultivated soil partially neutralize acids and form dry sulfate and nitrate salts Wet acid deposition (droplets of H2SO4 and HNO3 dissolved in rain and snow) Nitric oxide (NO) Dry acid deposition (sulfur dioxide gas and particles of sulfate and nitrate salts) Sulfur dioxide (SO2) and NO Acid fog Farm Lakes in shallow soil low in limestone become acidic Ocean Lakes in deep soil high in limestone are buffered Acid Rain formation

30 Which location does sulfuric & nitric acids transform?
Wind X Z Y Farm Ocean Which location does sulfuric & nitric acids transform?

31 Identify the type of acid deposition at point Y
Wind Transformation to sulfuric acid (H2SO4) and nitric acid (HNO3) Z Y Farm Ocean Identify the type of acid deposition at point Y

32 Identify the type of acid deposition at point Z
Wind X Z Dry acid deposition Farm Ocean Identify the type of acid deposition at point Z

33 Wind X Wet acid deposition Y Farm Ocean Great Job!!

34 Which chemicals lower the pH of rain?
Primary Pollutants CO CO2 Secondary Pollutants SO2 NO NO2 SO3 Most hydrocarbons HNO3 H2SO4 Most suspended particles H2O2 O3 PANs SO4 2 Most NO3 and salts Sources Natural Stationary Mobile Which chemicals lower the pH of rain?

35 Secondary Pollutants in RED
Primary Pollutants CO CO2 Secondary Pollutants SO2 NO NO2 SO3 Most hydrocarbons HNO3 H2SO4 Most suspended particles H2O2 O3 PANs SO4 2 Most NO3 and salts Sources Natural Stationary Mobile Secondary Pollutants in RED

36 pH levels of US soil

37 Effects of Acid Rain Decrease soil pH (more acidic)
Decrease pH of rivers, lakes, ponds, etc Fish kills Lung/respiratory problems Degrade metal pipes, leading to water pollution Plants become susceptible to disease, parasites, etc

38 Acid Rain Prevention and Solution
Solutions Acid Deposition Prevention Cleanup Reduce air pollution by improving energy efficiency Add lime to neutralize acidified lakes Reduce coal use Add phosphate fertilizer to neutralize acidified lakes Increase natural gas use Increase use of renewable resources Acid Rain Prevention and Solution Burn low-sulfur coal Remove SO2 particulates, and Nox from smokestack gases Remove Nox from motor vehicular exhaust Tax emissions of SO2

39 20.5 Indoor Air Pollution

40 Go outside and play Indoor air is typically a greater threat
People are inside up to 98% of their time Less air flow to remove pollutants Top pollutants: cigarette smoke, formaldehyde, radon, particulate matter. “Sick building” Typically newer buildings because of less air leaks. Symptoms: headache, coughing, sneezing, tiredness.

41 Formaldehyde Found in: plywood, furniture, upholstery, floor adhesives, dry cleaning chemicals. Causes: breathing problems, headache, sore throat, dizziness, eye irritation in those sensitive to low levels. Chronic exposure to higher levels can lead to cancer. Radon Naturally occurring from radioactive decay of U-238. Occurs in soils, bedrock and can get into homes through cracks. Can’t get out and builds up Can lead to lung cancer

42 1, 1, 1- Nitrogen Oxides: Tobacco Smoke Carbon Monoxide
Para-dichlorobenzene: air fresheners, moth balls; cancers Tetrachloroethylene: dry cleaning residue; nerve, liver, kidney problems Chloroform: chlorine-treated hot water; cancers Formaldehyde: from processed wood; eye, nose, throat, lung irritant 1, 1, 1- Trichloroethane: aerosals; dizziness, irregular breathing Benzo-a-pyrene: from smoke; lung cancer Nitrogen Oxides: Gas ovens, kerosene heaters, un-vented gas burning; lung irritation, headaches Styrene: from carpet/plastic. Kidney/liver problems Tobacco Smoke Asbestos: old floor tile, Pipe insulation; lung problems, cancer Radon-222: from soils, lung disease Carbon Monoxide Methylene Chloride: paint stripper, thinner; nerve, diabetes

43 Solutions Indoor Air Pollution Prevention Cleanup Cover ceiling tiles and lining of AC ducts to prevent release of mineral fibers Use adjustable fresh air vents for work spaces Ban smoking or limit it to well-ventilated areas Increase intake of outside air Change air more frequently Set stricter formaldehyde emissions standards for carpet, furniture, and building materials Circulate building’s air through rooftop greenhouses Prevent radon infiltration Use exhaust hoods for stoves and appliances burning natural gas Use office machines in well-ventilated areas Use less polluting substitutes for harmful cleaning agents, paints, and other products Install efficient chimneys for wood-burning stoves

44 Particulates - Aka: particulate matter (PM)
What are they? aerosols or fine particles, are tiny particles of solid (a smoke) or liquid (an aerosol) suspended in a gas. Size: < 10 nm - > 100 µm in diameter. Who do they effect? Sensitive populations such as children, the elderly, and individuals suffering from respiratory disease.

45 Particulate Matter (PM)
Larger particles are generally filtered in the nose and throat and do not cause problems. PM smaller than about 10 µm, referred to as PM10, can settle in the bronchi and lungs and cause health problems.

46 Particulate Matter (PM)
Includes a wide range of pollutants – road dust diesel soot fly ash wood smoke sulfate aerosols (suspended as particles in the air) These particles are a mixture of visible and microscopic solid particles and minute liquid droplets known as aerosols.

47 Take a deep breath… Asthma: on the rise! WHY?? Varying opinions:
Overly sterile environment as children; don’t build up natural immunity Exposure to allergens Genetic make up Exposure to pollution Lung cancer Chronic bronchitis Emphysema

48 National Ambient Air Quality Standards (NAAQS)
Standards established by the EPA that apply for outdoor air throughout the country. Primary standards are designed to protect human health. Secondary standards are designed to protect public welfare (e.g. building facades, visibility, crops, and domestic animals).

49 EPA’s watchful eye NAAQS requires the EPA to set standards on six criteria pollutants: Ozone (O3) Particulate Matter Carbon monoxide (CO) Sulfur dioxide (SO2) Nitrogen oxides (NOx) Lead (Pb)

50 Temperature Inversions (pg. 442) and Heat Islands (online activity)

51 Temperature Inversion
Warmer air Inversion layer Increasing altitude Cool layer Mountain Mountain Valley Decreasing temperature Traps pollutants near surface. Mountains prevent wind in area and shadow sun to keep lower air cool.

52 Temperature Inversion
Descending warm air mass Inversion layer Increasing altitude Sea breeze Mountain range Decreasing temperature Traps pollutants near surface. Mountains prevent pollutants leaving. Sea breeze blows in, not out This is what is happening in LA Video clip

53 20.7 Preventing and Reducing Air Pollution

54 Stationery Source Air Pollution
Solutions Stationery Source Air Pollution Prevention Dispersion or Cleanup Burn low-sulfur coal Disperse emissions above thermal inversion layer with tall smokestacks Remove sulfur from coal Convert coal to a liquid or gaseous fuel Remove pollutants after combustion Shift to less polluting fuels Tax each unit of pollution produced

55 Out-put or Control Methods
See text pg Fig 20-18

56 Cleaned gas Electrodes Dust discharge Dirty gas Electrostatic Precipitator – static plates collect particles

57 Bags Cleaned gas Dirty gas Dust discharge Baghouse Filter – only one to remove hazardous fine particles

58 Wet Scrubber – Expensive
Dirty gas Cleaned gas Clean water Wet gas Dirty water Remove 98% of SO2 and PM from emissions Wet Scrubber – Expensive

59 Cyclone Separator - Cheap
Cleaned gas Dirty gas Does NOT produce hazardous materials like other Dust discharge Cyclone Separator - Cheap

60 Solutions for mobile emissions
Motor Vehicle Pollutions Solutions for mobile emissions Prevention Cleanup Mass transit Emission control devices Bicycles and walking Less polluting engines Less polluting fuels Improve fuel efficiency Car exhaust Inspections twice a year Get older, polluting cars off the road Give buyers tax write- offs for buying low- polluting, energy- efficient vehicles Restrict driving in polluted areas Stricter emission standards

61 Solutions Air Pollution Prevention Cleanup Improve energy efficiency to reduce fossil fuel use Reduce poverty Distribute cheap and efficient cookstoves to poor families in developing countries Rely more on lower-polluting natural gas Rely more on renewable energy (especially solar cells, wind, and solar-produced hydrogen) Reduce or ban indoor smoking Develop simple and cheap test for indoor pollutants such as particulates, radon, and formaldehyde Transfer technologies for latest energy efficiency, renewable energy, and pollution prevention to developing countries.

62 Clean Air Acts US Congress in 1970, 1977, 1990
EPA regulation of emissions that contribute to global warming, ozone depletion and air pollution. View clip You should read ALL case studies in the chapter! Ea: The Bad Old Days, A Burning Controversy and section 20-7 specifically.

63 VI. Pollution (25-30%) Air pollution
Sources-primary and secondary (20.2 & air pollution lab) major air pollutants (20.2 & pollutant chart) measurement units (air pollution lab & emissions trading game) smog (20.3 & Demo: Smog in a jar) acid deposition-causes and effects (20.4, pH/acid rain lab, video) heat islands (online activity) and temperature inversions (20.3) indoor air pollution (20.5 &  air particulate lab) remediation and reduction strategies (air pollution allowance trading article, emissions trading game) and Fig ) Clean Air Act and other relevant laws (Law sheet, NAAQS)

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