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LECTURE 01 Cast of Characters

LECTURE 01 Cast of Characters. AOSC 434 Air Pollution Russell R. Dickerson www.atmos.umd.edu/~russ/syllabus434.html. London killer smog. Donora, PA October 29, 1948; 2:00pm LST. 1950 ’ s local – 2000 ’ s global. Washington Post Jan. 25, 2014

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LECTURE 01 Cast of Characters

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  1. LECTURE 01Cast of Characters AOSC 434 Air Pollution Russell R. Dickerson www.atmos.umd.edu/~russ/syllabus434.html

  2. London killer smog

  3. Donora, PA October 29, 1948; 2:00pm LST

  4. 1950’s local – 2000’s global.

  5. Washington Post Jan. 25, 2014 “China’s air pollution prompts creative, sometimes wacky, solutions”

  6. Pollution and Smog Seinfeld & Pandis Ch. 2 Finlayson-Pitts & Pitts Ch. 1 Wark & Warner Ch. 1 Jacob Chapters 12 & 13.

  7. Definitions • Los Angeles Smog (photochemical smog) is the mixture of ozone, hydrocarbons, partially oxidized hydrocarbons, oxides of nitrogen and other trace gases that results from the action of sunlight on automobile exhaust and other pollutants. It is characterized by high temperatures stagnant winds (high barometric pressure), and sunny conditions. • London Smog (particulate, or sulfurous smog) is a mixture of sulfur dioxide and sulfate and sulfite aerosol resulting primarily from the combustion of high sulfur coal followed by conversion of SO2 to H2SO4. It is characterized by low temperatures, high humidity and stagnant winds.

  8. Air PollutantsPhotochemical and London Smog Species Involved Including Criteria Pollutants Limit here refers to the National Ambient Air Quality Standard (NAAQS) established by the US-EPA.

  9. 1. Ozone, O3 (Photochemical Oxidant)criteria pollutant Secondary • Effects: 1. Respiration - premature aging of lungs (Bascom et al., 1996); mortality (e.g., Jerrett et al., 2009). 4%/10ppb 2. Phytotoxin, i.e. Vegetation damage (Heck et al., JAPCA., 1982; Schmalwieser et al. 2003; MacKinzie and El-Ashry, 1988) 3. Materials damage - rubber 4. Greenhouse effect (9.6 m) • Limit: (National Ambient Air Quality Standard) 80 ppb for 1 hr. 1971 120 ppb for 1 hr. 1979 84 ppb for 8 hr 1997 75 ppb for 8 hr 2010 65 ppb on the books. • Ozone is an indicator of smog. • Ozone regulates many other oxidants

  10. Ozone damaged plants.

  11. What does history tell us? • Denora, Pitt, and London were sulfurous smogs. • Early work in Los Angeles focused on SO2 from refineries – smog got worse. • VOC’s targeted next – smog got worse. • Denora, London, etc. were worse in winter – LA was worse in summer. • Burning eyes in LA.

  12. What does history tell us? P. L. McGill, Stanford Research Institute*, “The Los Angeles Smog Problem”Industrial and Engineering Chemistry, 2476-86, 1949. “Unquestionably the most disagreeable aspect of smog is eye irritation.” They blamed elemental sulfur. Mechanism of the Smog:“Weather conditions control the time of occurrence of eye-irritating smog in Los Angeles.”Meteorology and topography. Identified temperature inversions and stagnant winds as contributors. No mention of combustion, ozone, photochemistry, or automobiles other than as a source of H2CO that did not cause eye irritation. *supported by The Western Oil and Gas Association.

  13. Haagen-Smit (1952) “Photochemical action of nitrogen oxides oxidized the hydrocarbons and thereby forms ozone….” Almost right.

  14. Ozone is a national problem

  15. 2. Nitrogen Dioxide, NO2criteria pollutant Primary Effects: 1. Lungs (acute chemical pneumonia) EPA Criteria Pollutant 2. Phytotoxin 3. Catalyst for ozone formation. 4. Atmospheric acidity (about 1/3 of problem and growing) Limit: 100 g m-3 (53 ppb) annual mean 200 g m-3 (100 ppb) hourly mean (2010)

  16. 3. Carbon Monoxide, COcriteria pollutant Primary Effects: 1. Respiration (acute); EPA Criteria Pollutant 2. Cardiovascular system (chronic) 3. Contributor to photochemical smog 4. Changes global HOx cycle (oxidizing capacity of atmosphere). Limits: 9.0 ppm for 8 hr 35 ppm for 1 hr 50 ppm for 8 hr is the "level of significant harm"

  17. 3. Carbon Monoxide, CO (cont…) • Affinity for hemoglobin 200 times that of O2. • Displaces O2 at [CO] = 0.2x106/ 200 = 103 ppm. • Concentrations above 750 ppm are fatal. • Concentrations > 100 ppm cause dizziness, headache, loss of visual & mental acuity. • Cigarette smoke contains ca. 400 ppm CO (also HCN, H2CO, Ni(CO)4, NO2).

  18. 4. Peroxyacetyl Nitrate, "PAN" (CH3 C(O)-O-O- NO2)not a criteria pollutant Secondary Effects: 1. Eye irritation 2. Respiratory tract (carcinogen?) 3. Phytotoxin   Limits: None (too hard to measure) • Compound "X" in LA smog • NOx reservoir.

  19. An interesting history Smogtown, by Jacobs and Kelly, Overlook Press, 2008.

  20. 5. Polynuclear Aromatic Hydrocarbons, "PAH"(Also Polycyclic Aromatic Hydrocarbons) See Also Finlayson-Pitts Chapt. 9&10. Primary Effects: 1. Carcinogenic (one of the few known carcinogens in air)   Limits: None • Low/moderate vapor pressure; divided between particulate & gas-phases. • Example: Benzo(a)pyrene (BaP) • Nitrated PAH even stronger carcinogens .

  21. 6. Ethylene, H2C=CH2 Primary Effects: 1. Ozone formation 2. Plant hormone (e.g. oranges)   Limits: None • Other biogenic hydrocarbons, isoprene, pinenes. • Some plants when stressed release more ethylene

  22. 7. Formaldehyde, H2CO Primary and secondary Effects: 1. Ozone formation 2. Eye irritant 3. Mutagen, suspected carcinogen   Limits: None • Indoor air pollutant too, (ureaformaldehyde insulation) • Produced by HC oxidation • Represents class of partially oxidized HC

  23. 8. Lead, Pbcriteria pollutant Primary Effects: 1. Toxic, leads to loss of mental acuity. Limits: 0.15 µg/m3 rolling three month average. Now primarily a problem of the developing world.

  24. 9. Other Pollutants (toxics) Halogenated Hydrocarbons Example: Dioxin Effects: 1. Teratogen 2. LD50 in guinea pigs is 0.5 to 1.0 g/kg   Limits: None • Produced as byproduct in 2,4-D and 2,4,5-T synthesis and by incompletecombustion of chlorine containing refuse such as plastics. • "Freons" will be considered as part of stratospheric air pollution.

  25. LONDON-TYPE SMOG 10. Sulfur Dioxide, SO2 Primary Effects 1. Produces H2SO4 found on particles and in precipitation - Acid Deposition 2. Cloud Condensation Nuclei (climate) 3. Materials degradation 4. Respiratory tract (esp. bisulfites, HSO3-) 5. Phytotoxin

  26. 10. Sulfur Dioxide, SO2 (cont…) Limits: Primary 1-hr Standard: 75 ppb (June 2010) Secondary standard 500 ppb for 3 hr SO2 (HSO3-)aq H2SO4 (+ NH3)  NH4HSO4 (+ NH3)  (NH4)2SO4 • EPA Criteria Pollutant • No catalytic photochemistry • More on chemistry and physics later

  27. 11. Fine Particulate Matter (PM2.5) Aerodynamic Diameter < 2.5 μm Limits: 35 μg m-3 for 24 hr 12 μg m-3 annual mean (150 μg m-3 for 24 hr for PM10) • Primary and secondary pollutants. • Major health effects: • More on chemistry and physics later

  28. Wet deposition of sulfate

  29. 12. Carbon Dioxide, CO2 Primary Non toxic below percent levels. Dominant greenhouse gas.

  30. Health Effects3 Steps for Estimating • Epi Study determines C-R function • Estimate incidences and change in exposure • Calculate deaths and assign a value

  31. Local, Regional, Global Pollution Before 1950s: Local Smoke, Fly ash • Post- 2000s: • Global • Global Change 1970s-1990s: Regional Acid Rain, Haze

  32. Lecture Summary There are a variety of pollutants. They have health and environmental or welfare effects. You will be expected to know the name and basic facts of each pollutant or pollutant family. This course will provide you with the tools to understand the impact, sources, chemistry, transport, trends, and sinks for all of these pollutants – and some that have not been discovered yet.

  33. TROPOSPHERIC Ozone Photochemistry CLEAN AIR (1) O3 + h O2 + O(1D) (2) O(1D) + H2O  2OH (3) OH + O3 HO2 + O2 (4) HO2 + O3 2O2 + OH ----------------------------------------- (3+4) 2O3 3O2 NET

  34. DIRTY AIR (3') OH + CO  H + CO2 (4') H + O2 + M  HO2 + M (5') HO2 + NO  NO2 + OH (6') NO2 + h NO + O (7') O + O2 + M  O3 + M ------------------------------------------------- (3'-7') CO + 2 O2 CO2 + O3 NET

  35. Similar Reaction Sequence For Methane CH4 + OH  CH3 + H2O CH3 + O2 + M  CH3O2 + M CH3O2 + NO  NO2 + CH3O CH3O + O2 H2CO + HO2 HO2 + NO  NO2 + OH NO2 + h NO + O O + O2 + M  O3 + M ---------------------------------------------------------------------- CH4 + 4 O2 + h 2 O3 + H2CO + H2O NET

  36. What Is The Fate Of Formaldehyde? 2H2CO + h H2 + CO  HCO + H H + O2 + M  HO2 + M HCO + O2 HO2 + CO -------------------------------------------- 2H2CO + 2O2 2CO + 2HO2 + H2

  37. This means two ozone molecules are produced per formaldehyde. The grand total for methane is four O3 produced! Methane is a good model for all alkanes, but by itself reacts too slowly to form much ozone locally, it is, however, important on a global scale. The net production of ozone requires converting of NO to NO2 without consuming O2.

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