Smog

1. Smog Los Angeles Pittsburgh Dallas

2. Causes of Smog Smog is caused by: • Smoke Particles • Ozone • NO2 • Many others

3. Pittsburgh • Has always been known as a smoky town • Still beats L.A and Dallas for air pollution

4. Pittsburgh 1944 • Had many steel mills and made widespread use of cheap West Virgina coal

5. Pittsburgh • The hills trapped the smog and sometimes turned day into night. 8:40 AM , 1932 11:00 AM 1949

6. Donora, Pa. • Worst air pollution disaster in the United States • Killer smog on Halloween 1948 • Started the clean air movement US Steel open hearth furnace, Donora, Pa. Donora, 1946

7. Donora, Pa. • The Largest Zinc Smelting plant in the world, and a U.S. Steel plant too • All in the Monongahela River valley, surrounded by hills

8. The Donora Disaster • October 27, 1948 • Thick smoky fog lasted for 5 days • Couldn’t see Halloween parade • 70 people died in a week • 6,000 were medically treated because they couldn’t breathe • Population was only 14,000 • Only 2 hospitals and 8 doctors in town • CO2, NO2, SO2, and F2 were all to blame

9. Donora, Pa. • Donora is remembered as a key event that inspired federal air pollution legislation in the 1960s and 1970s. • It contributed indirectly to the establishment of the U.S. Environmental Protection Agency in 1970. Donora, Noon, 1948 Regulations were put into place and by 1955 the Pittsburgh area had cleaned up emissions by 97 percent. In 1963, the United States Congress passed the Clean Air Act.

10. Pittsburgh • Local regulations and the Clean Air Act of 1963 has had a visible impact 1954 - Liberty Tunnel – vs 1965

11. Pittsburgh today 2009

12. What makes smog so bad? • Smog consists of NOX (NO2) and Ozone (O3) • It is extremely toxic and corrosive. Virtually all the plant life was dead for a ½ mile around Donora even before 1948.

13. What makes smog so bad? • Repeated exposure may permanently damage lungs or aggravate respiratory infections. • It reduces lung function or aggravates existing respiratory conditions such as asthma, emphysema or bronchitis. • It causes chest pain, coughing, throat irritation or congestion.

14. Let’s look at NO2 • Why is it so bad? • Why is it so reactive? • How many valence electrons does it have? • 5 + 2(6) = 17 electrons • It’s an odd number • 8 pairs and one more electron

15. Lewis Structure of NO2 8 ½ pairs of electrons

16. Lewis Structure of NO2 Extra stability added due to resonance But still not the most stable compound around Bent molecular structure

17. Formation of N2O4 Sometimes two NO2 molecules combine to form N2O4 The Nitrogen has a full octet now. It makes the molecule more stable, but it must not be too strong, because it takes very little temperature to break it.

18. A constantly shifting balance or equilibrium reaction As the weather temperature climbs into the 100oF range, the N2O4 breaks back apart into NO2. N2O4  NO2 Clear gas Cold days Less reactive Full octet Red-Brown Gas Hot Days More reactive Odd # electrons

19. NO2 rears its head on hot days As the temperature climbs into the 100oF range, a reddish brown haze appears in the sky if NO2 is present.