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What did we get from the last lecture? Ozone What is the role of ozone in the atmosphere?

What did we get from the last lecture? Ozone What is the role of ozone in the atmosphere? ground level = damaging upper atmosphere = protective What is UV radiation? UVA and UVB What does ozone have to do with UV? What do chlorofluorocarbons have to do with this?. Why should this matter?

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What did we get from the last lecture? Ozone What is the role of ozone in the atmosphere?

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  1. What did we get from the last lecture? • Ozone • What is the role of ozone in the atmosphere? • ground level = damaging • upper atmosphere = protective • What is UV radiation? • UVA and UVB • What does ozone have to do with UV? • What do chlorofluorocarbons have to do with this?

  2. Why should this matter? • Human health effects • Skin Cancer: damage to photosensitive tissue • Types of skin cancer: squamous cell and basal cell probably won’t kill you but malignant melanoma can • Animal health effects • All organisms can be adversely affected by U.V. • Plants won’t know what to do • Generally good at dealing with radiation but levels are not what they have been exposed to throughout evolution

  3. Timeline of events 1974: Figure out they could be trouble 1979: Ban as propellant 1984: Evidence of thinning 1987: Montreal Protocol 1996: Phase out continues 2006: Cease production Why did this work? Data easier to interpret and less economic investment

  4. Thus ends the exam material • But how is ozone which is good in one place bad at ground level? • Ozone is a reactive molecule: • Damages plants • Irritates animal tissue • Destroys materials • Ozone is one of many ground level air pollutants

  5. Air Pollutants and their sources

  6. Smog and its constituents Smog = smoke and fog Industrial smog Historically the first (factories before cars) Has killed the most (Donora, PA for one) Less common in US today the legacy remains (acid precip in a bit)

  7. Clean Air Act of 1970 • Establishes the “criteria pollutants” • Sets NAAQS • Originally to address industrial smog

  8. Photochemical smog • Automobile smog • Most prevalent in US • No longer restricted to “warm basin cities” • (but that is where it is the worst)

  9. How does it form? • NO2: can react with U.V. to release: NO and O • Remember O? highly reactive • Can react with other gasses in atmosphere to give rise to • Ozone • PANs (like tear gas) • Aldehydes as well • all are irritating to the respiratory tract

  10. Thermal Inversions • Convection currents normally dilute ground level pollutants

  11. Thermal Inversion (like in Donora) traps them

  12. Improvement of air quality in the US • The Clean Air Act of 1970 (’63, ‘77, and ’90 and so on) • Taller smoke stacks and reduced particulate emissions: • “Dilution” is not a viable solution • Reduce smog and raise clean air standards • Reduce sulfate and nitrate (but you can trade them) • Reduce car emissions and evaporated hydrocarbons • Car emission controls and low emission vehicles • PA program: • (http://www.dep.state.pa.us/dep/deputate/airwaste/aq/afv/afvafig1.htm)

  13. “Clear Skies”? • Currently in the Senate • Does not address carbon dioxide (but the Clean Air Act doesn’t either • Expands pollution trading • Role back of New Source Review – net result projected to be increased emissions

  14. Industrial smog has a legacy: • Top 50 Sulfur Dioxide Producers are East of the Mississippi • Acid Deposition: Why, where and how? • Why is this a problem? • What is an acid and what is the normal pH of life? • How does it form?

  15. Why, where and how? Where and how this is a problem? Aquatic systems: acid shock and chronic exposure Trees and plants Areas with thin already acid soils Altered mobility of nutrients and toxic stuff Human structures We sit smack dab in the middle

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