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Environmental Science

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Presentation on theme: "Environmental Science"— Presentation transcript:

1 Environmental Science
Chapter 12 Air Pollution

2 Key Concepts Structure and composition of the atmosphere
Types and origins of major outdoor air pollutants Two types of smog Acid deposition and how it can be reduced Harmful effects of air pollutants Preventing and controlling air pollution

3 Reminders… Troposphere  lower atmosphere; extends from the Earth’s surface up to 11 miles high Stratosphere  upper atmosphere; extends 11 to 30 miles above the Earth’s surface Troposphere: -most of the air is composed of nitrogen (78%) and oxygen (21%) -contains 75-80% of Earth’s air Stratosphere: -similar in composition to troposphere except it contains much less water vapor and higher levels of ozone

4 Outdoor Air Pollution Def: presence of one or more chemicals in the atmosphere in sufficient quantities and duration to cause harm to humans or other living organisms Primary vs Secondary Pollutants A. Primary  those emitted directly into the troposphere in a potentially harmful form B. Secondary  formed when primary pollutants react with one another or other components of air Air pollution: -can come from both natural (ex: forest fires, volcanoes) and human sources (ex: burning fossil fuels) Primary pollutant: -example: carbon monoxide Secondary pollutant: -example: ozone

5 Sources and Types of Air Pollutants
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 Fig. 15-3, p. 348

6 Outdoor Air Pollution Cities normally have higher air pollution than rural areas but winds can transport pollutants to these areas United States has government-mandated standards for maximum allowable atmospheric concentrations for six major pollutants Acid Rain Poland

7 Outdoor Air Pollution (Table 15-1)
A. Carbon Monoxide Sources: smoking/burning of fossil fuels Health Effects: reduce ability of red blood cells to carry oxygen; negatively impact the development of fetuses/young children; aggravate existing healthy conditions; cause headaches/nausea B. Nitrogen Dioxide Sources: burning of fossil fuels Health Effects: cause irritation/damage to lungs; increase susceptibility to respiratory diseases; aggravate existing lung disorders such as asthma Environmental Effects: can form nitric acid in atmosphere which is a major component of acid rain; may reduce visibility

8 Outdoor Air Pollution C. Sulfur Dioxide
Sources: burning of fossil fuels Health Effects: cause breathing problems and bronchitis-like condition; aggravate asthma symptoms Environmental Effects: can form sulfuric acid in atmosphere, another component of acid rain D. Suspended Particulate Matter (SPM) Sources: burning of fossil fuels, agriculture, unpaved roads, construction Health Effects: cause respiratory irritation/bronchitis; aggravate existing respiratory conditions; lead to early death, cancer or mutations depending on chemicals contained within (ex: lead)

9 Outdoor Air Pollution E. Ozone F. Lead
Sources: chemical reaction with volatile organic compounds and nitrogen oxides Health Effects: cause respiratory irritation; aggravate existing respiratory conditions; suppress immune system F. Lead Sources: paint, metal refineries, storage batteries, leaded gas, etc. Health Effects: damage to brain and nervous system; cancer; mental retardation

10 Smog Two Types: A. Photochemical (Brown) Smog
Pollutants formed with the aid of sunlight Forms when nitrogen oxides (NOx) and volatile organic compounds (VOCs) react with UV light Mixture of >100 chemicals but the most abundant of these is ozone (termed ground-level ozone) - The hotter the day, the higher the level of smog! Since 1990, levels of this type of smog has increased 2 to 8 times Origins are automobile exhaust and coal-burning power and industrial plants Most common in cities with warm, sunny, dry climates with lots of motor vehicles/industry Ex: LA, Denver and Salt Lake City

11 Animation Formation of photochemical smog

12 Los Angeles

13 Smog B. Industrial (Gray) Smog
Consist mostly of sulfur dioxide, sulfuric acid droplets and aerosols Found in cities with industries that burn a lot of fossil fuels Tall smoke stacks and pollution control mechanisms in developed countries have greatly reduced this type of air pollution. - BUT still a major problem in developing countries, like China and India.

14 Industrial Smog in India
Fig. 15-5, p. 351

15 “Asian brown cloud” can be up to a three kilometres thick and stretches from India to Western Pacific Causes: Asia's explosive industrial development Sources include: vehicular and industrial emission, burning of millions of little cookers in peoples' homes, burning wood or dung Results: respiratory diseases and premature deaths Prevents up to 15% of sunlight from reaching the ground Changing weather patterns Negatively affects western U.S. air quality As much as 10% of air pollutants in LA comes from SE Asia!!!

16 Smog Factors Influencing Smog Formation: Local Climate/Topography
Population Density Amount of industry Type of fuels consumed Local climate/topography: -winds and rain/snow reduce the level of smog -hills/mountains, urban buildings and high temperatures can increase it Population density: -more people=more smog So, because Florida has a low topography, good air circulation, high humidity, and lots of rain, smog is rarely a problem here!

17 Air Pollution Website depicts the air quality index (AQI) for select cities or locations throughout the United States EPA calculates the AQI for five major air pollutants regulated by the Clean Air Act: ground-level ozone, particle pollution (also known as particulate matter), carbon monoxide, sulfur dioxide, and nitrogen dioxide. Symbolized by color: 0 to 50  Good  Green 51 to 100  Moderate  Yellow 101 to 150  Unhealthy for Sensitive Groups  Orange 151 to 200  Unhealthy  Red 201 to 300  Very Unhealthy  Purple 301 to 500 Hazardous  Maroon

18 Air Quality - Florida Florida DEP website (
Contains air quality information for different cities and counties in Florida Osceola County From 2001 to 2003 for Ozone: 97.6% of days were good (green) 2.2% of days were moderate (yellow) 0.2% of days were unhealthy for sensitive groups (orange)

19 Acid Deposition Primary pollutants are sulfur dioxide and nitrogen oxides which can react with other atmospheric compounds to produce acidic substances that can remain in the atmosphere for up to two weeks! Acidic substances can descend to the Earth in two forms: A. Wet  ex: rain, snow, fog B. Dry  shorter time frame (<3 days)

20 Acid deposition

21 pH Measurements at US Sites
Fig. 15-7, p. 354

22 Acid Deposition Effects: 1. Respiratory problems in humans
2. Damages property 3. Lakes and Streams  Acid rain causes a cascade of effects that harm or kill individual fish, reduce fish population numbers, completely eliminate fish species from a waterbody, and decrease biodiversity. U.S. govt investigated the effects of acidic deposition in over 1000 lakes larger than 10 acres and in thousands of miles of streams believed to be sensitive to acidification. - of these, acid rain caused acidity in 75% of the acidic lakes and 50% of acidic streams - several “hot spots” include Adirondacks and Catskill Mtns in New York, the mid-Appalachian highlands along the east coast, the upper midwest, and mountainous areas of the western U.S. - one of the most acidic lakes reported was Little Echo Pond in Franklin, NY, which had a pH of 4.2

23 Acid Deposition 4. Trees  acid rain causes slower growth, injury, or death of forests. 5. Corrosion of metals (such as bronze) and the deterioration of paint and stone (such as marble and limestone). 6. Reduced visibility Trees: - Acid rain has been implicated in forest and soil degradation in many areas of the eastern U.S., particularly high elevation forests of the Appalachian Mtns from Maine to Georgia that includes areas such as the Shenandoah and Great Smoky Mtn NP Reduced visibility: - The U.S. govt’s Acid Rain Program is expected to improve the visual range in the eastern U.S. by 30% - The visual range improvements expected at national parks of the eastern U.S. due to the Acid Rain Program’s SO2 reductions will be worth over a billion dollars annually by the year 2010.

24 Tree Damage from Acid Deposition
Mt. Mitchell, NC – the highest point east of the Mississippi Fig , p. 356

25 Acid Deposition Obviously, the best approach to reduce acid rain is to reduce emission of the chemicals that cause it (sulfur dioxide and nitrogen oxides) What you can do (EPA): Turn off lights, computers, and other appliances when you're not using them Use energy efficient appliances: lighting, air conditioners, heaters, refrigerators, washing machines, etc. Only use electric appliances when you need them. Keep your thermostat at 68 F in the winter and 72 F in the summer. You can turn it even lower in the winter and higher in the summer when you are away from home. Insulate your home as best you can. Carpool, use public transportation, or better yet, walk or bicycle whenever possible Buy vehicles with low NOx emissions, and maintain all vehicles well.

26 Reducing Acid Deposition
© 2006 Brooks/Cole - Thomson 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 Burn low-sulfur coal Remove SO2 particulates, and Nox from smokestack gases Remove Nox from motor vehicular exhaust Tax emissions of SO2 Fig , p. 357

27 Major Indoor Air Pollutants
Para-dichlorobenzene Chloroform Tetrachloro-ethylene Formaldehyde 1, 1, 1- Trichloroethane Styrene Nitrogen Oxides Benzo-a-pyrene Particulates Tobacco Smoke Radon-222 Asbestos Carbon Monoxide Methylene Chloride Fig , p. 358

28 Indoor Air Pollution Most Dangerous:
A. Formaldehyde  colorless gas used in the manufacturing of many common household materials, such as furniture, drapes, plywood, and paneling B. Radon Gas  colorless, odorless gas that is found naturally in underground deposits of minerals (e.g., uranium, phosphate) and seeps up through the soil and into homes via cracks, openings or through concrete blocks Formaldehyde: EPA estimates that one out of every 5,000 people living in a manufactured home for more than 10 yrs will develop cancer from formaldehyde exposure! Radon: EPA recommends that all homes be tested for radon Second leading cause of lung cancer One in 15 homes in the U.S. has a high level of radon

29 Outlet vents for furnaces and dryers
Radon Open window Openings around pipes Cracks in wall Slab joints Wood stove Cracks in floor Sump pump Clothes dryer Furnace Slab Radon-222 gas Uranium-238 Soil Fig , p. 359

30 Effects of Air Pollution
Humans: Break down natural defenses and lead to respiratory diseases such as lung cancer, asthma, chronic bronchitis and emphysema Plants: Forest diebacks (due to depletion of nutrients in soil and increased susceptibility to pests and diseases) Estimated $2-6 billion in agricultural losses due to air pollution (mainly ozone)

31 Effects of Air Pollution
Other: Deterioration of paint on cars/houses Damage to historical buildings, sculptures, etc. Cleaning costs due to soot/other particulates accumulating

32 Premature US Deaths from Air Pollution
In US, the EPA estimates that annual deaths related to indoor and outdoor air pollution range from 150,000 to 350,000 people. Fig , p. 361

33 Solutions Clean Air Acts of 1970, 1977 and 1990
Federal government established air pollution regulations EPA was the agency charged with developing and enforcing air regulation standards - Established NAAQS (National Ambient Air Quality Standards) for six major pollutants which specifies the maximum allowable level for each. - Also established emission standards for more than 188 hazardous air pollutants. - These acts have helped to greatly improve air quality in the U.S. but many people are still living in dangerously polluted areas.

34 Solutions Improvements still needed:
Focus more on prevention than clean-up Increase fuel efficiency standards for automobiles, especially SUVs and trucks Better regulation of emissions from 2-cycle engines (e.g., outboard motors, jet skis, lawnmowers, chainsaws) Do more to decrease emission of greenhouse gases Indoor air pollution control Better enforcement Prevention: -the 97% reduction in lead between 1970 and 1998 was due to the ban on leaded gasoline 2-cycle engines: A 1-hr ride on a typical jet ski creates more air pollution than the average car does in a year!

35 Emission Trading Policy
Sulfur Dioxide Emissions Each year a power plant is given a certain number of pollution credits to emit a certain amount of sulfur dioxide. You can even buy credits!!! If they use less than their limit, then they can use the credits for their own benefit (e.g., expand the size of a plant or offset the pollution at another plant) or sell them to other groups (e.g., private utilities, environmental groups). This policy has reduced sulfur dioxide emissions in the U.S. by 30% between 1994 and 1997!

36 Other Solutions Figures 15-17 through 15-21 Individual Actions:
Use mass transit Bike/walk when possible Use fuel efficient vehicles Don’t smoke indoors or in confined areas Increase ventilation and intake of outside air Install energy efficient appliances Use less polluting substitutes for cleaning agents, paints, etc. Outdoor Indoor

37 Websites Some alternatives to common pesticide chemicals/cleaners: More information on air pollution: Facts about alternative fuels:

38 Any Questions? News stories… Algal Fuel Transgenic Tobacco

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