2Key Concepts Structure and composition of the atmosphere Types and origins of major outdoor air pollutantsTwo types of smogAcid deposition and how it can be reducedHarmful effects of air pollutantsPreventing and controlling air pollution
3Reminders…Troposphere lower atmosphere; extends from the Earth’s surface up to 11 miles highStratosphere upper atmosphere; extends 11 to 30 miles above the Earth’s surfaceTroposphere:-most of the air is composed of nitrogen (78%) and oxygen (21%)-contains 75-80% of Earth’s airStratosphere:-similar in composition to troposphere except it contains much less water vapor and higher levels of ozone
4Outdoor Air PollutionDef: presence of one or more chemicals in the atmosphere in sufficient quantities and duration to cause harm to humans or other living organismsPrimary vs Secondary PollutantsA. Primary those emitted directly into the troposphere in a potentially harmful formB. Secondary formed when primary pollutants react with one another or other components of airAir pollution:-can come from both natural (ex: forest fires, volcanoes) and human sources (ex: burning fossil fuels)Primary pollutant:-example: carbon monoxideSecondary pollutant:-example: ozone
5Sources and Types of Air Pollutants Primary PollutantsCOCO2Secondary PollutantsSO2NONO2SO3Most hydrocarbonsHNO3H2SO4Most suspendedparticlesH2O2O3PANsSO42–MostNO3–andsaltsSourcesNaturalStationaryMobileFig. 15-3, p. 348
6Outdoor Air PollutionCities normally have higher air pollution than rural areas but winds can transport pollutants to these areasUnited States has government-mandated standards for maximum allowable atmospheric concentrations for six major pollutantsAcid RainPoland
7Outdoor Air Pollution (Table 15-1) A. Carbon MonoxideSources: smoking/burning of fossil fuelsHealth Effects: reduce ability of red blood cells to carry oxygen; negatively impact the development of fetuses/young children; aggravate existing healthy conditions; cause headaches/nauseaB. Nitrogen DioxideSources: burning of fossil fuelsHealth Effects: cause irritation/damage to lungs; increase susceptibility to respiratory diseases; aggravate existing lung disorders such as asthmaEnvironmental Effects: can form nitric acid in atmosphere which is a major component of acid rain; may reduce visibility
8Outdoor Air Pollution C. Sulfur Dioxide Sources: burning of fossil fuelsHealth Effects: cause breathing problems and bronchitis-like condition; aggravate asthma symptomsEnvironmental Effects: can form sulfuric acid in atmosphere, another component of acid rainD. Suspended Particulate Matter (SPM)Sources: burning of fossil fuels, agriculture, unpaved roads, constructionHealth Effects: cause respiratory irritation/bronchitis; aggravate existing respiratory conditions; lead to early death, cancer or mutations depending on chemicals contained within (ex: lead)
9Outdoor Air Pollution E. Ozone F. Lead Sources: chemical reaction with volatile organic compounds and nitrogen oxidesHealth Effects: cause respiratory irritation; aggravate existing respiratory conditions; suppress immune systemF. LeadSources: paint, metal refineries, storage batteries, leaded gas, etc.Health Effects: damage to brain and nervous system; cancer; mental retardation
10Smog Two Types: A. Photochemical (Brown) Smog Pollutants formed with the aid of sunlightForms when nitrogen oxides (NOx) and volatile organic compounds (VOCs) react with UV lightMixture 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 timesOrigins are automobile exhaust and coal-burning power and industrial plantsMost common in cities with warm, sunny, dry climates with lots of motor vehicles/industryEx: LA, Denver and Salt Lake City
13Smog B. Industrial (Gray) Smog Consist mostly of sulfur dioxide, sulfuric acid droplets and aerosolsFound in cities with industries that burn a lot of fossil fuelsTall 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.
15“Asian brown cloud” can be up to a three kilometres thick and stretches from India to Western PacificCauses:Asia's explosive industrial developmentSources include: vehicular and industrial emission, burning of millions of little cookers in peoples' homes, burning wood or dungResults:respiratory diseases and premature deathsPrevents up to 15% of sunlight from reaching the groundChanging weather patternsNegatively affects western U.S. air qualityAs much as 10% of air pollutants in LA comes from SE Asia!!!
16Smog Factors Influencing Smog Formation: Local Climate/Topography Population DensityAmount of industryType of fuels consumedLocal climate/topography:-winds and rain/snow reduce the level of smog-hills/mountains, urban buildings and high temperatures can increase itPopulation density:-more people=more smogSo, because Florida has a low topography, good air circulation, high humidity, and lots of rain, smog is rarely a problem here!
17Air PollutionWebsite depicts the air quality index (AQI) for select cities or locations throughout the United StatesEPA 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 Green51 to 100 Moderate Yellow101 to 150 Unhealthy for Sensitive Groups Orange151 to 200 Unhealthy Red201 to 300 Very Unhealthy Purple301 to 500 Hazardous Maroon
18Air Quality - Florida Florida DEP website (www.dep.state.fl.us/Air) Contains air quality information for different cities and counties in FloridaOsceola CountyFrom 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)
19Acid DepositionPrimary 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, fogB. Dry shorter time frame (<3 days)
22Acid Deposition Effects: 1. Respiratory problems in humans 2. Damages property3. 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
23Acid Deposition4. 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 visibilityTrees:- 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 NPReduced 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.
24Tree Damage from Acid Deposition Mt. Mitchell, NC – the highest point east of the MississippiFig , p. 356
25Acid DepositionObviously, 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 themUse 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 possibleBuy vehicles with low NOx emissions, and maintain all vehicles well.
27Major Indoor Air Pollutants Para-dichlorobenzeneChloroformTetrachloro-ethyleneFormaldehyde1, 1, 1-TrichloroethaneStyreneNitrogen OxidesBenzo-a-pyreneParticulatesTobacco SmokeRadon-222AsbestosCarbon MonoxideMethylene ChlorideFig , p. 358
28Indoor Air Pollution Most Dangerous: A. Formaldehyde colorless gas used in the manufacturing of many common household materials, such as furniture, drapes, plywood, and panelingB. 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 blocksFormaldehyde: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 radonSecond leading cause of lung cancerOne in 15 homes in the U.S. has a high level of radon
29Outlet vents for furnaces and dryers RadonOpen windowOpeningsaroundpipesCracks in wallSlab jointsWood stoveCracks in floorSumppumpClothesdryerFurnaceSlabRadon-222 gasUranium-238SoilFig , p. 359
30Effects of Air Pollution Humans:Break down natural defenses and lead to respiratory diseases such as lung cancer, asthma, chronic bronchitis and emphysemaPlants: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)
31Effects of Air Pollution Other:Deterioration of paint on cars/housesDamage to historical buildings, sculptures, etc.Cleaning costs due to soot/other particulates accumulating
32Premature 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
33Solutions Clean Air Acts of 1970, 1977 and 1990 Federal government established air pollution regulationsEPA 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.
34Solutions Improvements still needed: Focus more on prevention than clean-upIncrease fuel efficiency standards for automobiles, especially SUVs and trucksBetter regulation of emissions from 2-cycle engines (e.g., outboard motors, jet skis, lawnmowers, chainsaws)Do more to decrease emission of greenhouse gasesIndoor air pollution controlBetter enforcementPrevention:-the 97% reduction in lead between 1970 and 1998 was due to the ban on leaded gasoline2-cycle engines:A 1-hr ride on a typical jet ski creates more air pollution than the average car does in a year!
35Emission Trading Policy Sulfur Dioxide EmissionsEach 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!
36Other Solutions Figures 15-17 through 15-21 Individual Actions: Use mass transitBike/walk when possibleUse fuel efficient vehiclesDon’t smoke indoors or in confined areasIncrease ventilation and intake of outside airInstall energy efficient appliancesUse less polluting substitutes for cleaning agents, paints, etc.OutdoorIndoor
37WebsitesSome alternatives to common pesticide chemicals/cleaners:More information on air pollution:Facts about alternative fuels: