How Humans Affect the Atmosphere: Air Pollution and its Impacts

1. How Humans Affect the Atmosphere: Air Pollution and its Impacts Weather & Atmosphere – Meeting the BenchmarksCCISD, Hancock, MIFeb 15, 2002Richard E. HonrathDept. of Civil & Environmental EngineeringMichigan Technological University

2. The major air pollutants Carbon monoxide (CO) Nitrogen oxides (NOx) Ozone (O3) Particulate matter (PM-10, PM-2.5) Sulfur dioxide (SO2) Lead (Pb) Greenhouse gases (CO2 and others)

3. Carbon Monoxide • Impacts: Blood oxygen levels Hb + O2 <-> HbO2 K1 = Equilibrium constant Hb + CO <-> HbCO K2 = 210 x K1 • Headaches, alertness, death • Sources: Vehicles (plus others) Source: Ref. (1)

4. Carbon Monoxide • CO levels are improving, but still a problem in many colder urban areas. Source: Ref. (1)

5. Nitrogen Oxides • NOx = NO + NO2 • Impacts: Respiratory irritant (NO2) (but AQ standard seldom violated) • Leads to ozone formation • Leads to acidic deposition of HNO3

6. Nitrogen Oxides • NOx = NO + NO2 • Impacts: Respiratory irritant (NO2) • Leads to ozone formation • Leads to acidic deposition of HNO3 • Sources: High-temperature combustion N2 + O2  2NO Source: Ref. (1)

7. Ozone • Impacts: • Respiratory irritant • Plant damage (forest, crops) (FACE site) • Oxidizes C=C double bonds: rubber • Sources: • Produced in the atmosphere NOx + VOCs + sunlight -> NOx + O3

8. Ozone A major urban and regional pollution problem Source: Ref. (1)

9. Particulate Matter • Definitions: • PM10 = PM < 10 um • PM2.5 = PM < 2.5 um • Impacts: • Lung irritation • Visibility

10. Particulate Matter • Impacts: • Lung irritation • Visibility • Sources: Depends on particle size Source: Ref. (1)

11. Particulate Matter Impacts: Visibility at Shenandoah Nat’l Park Source: Ref. (2)

12. Sulfur Dioxide • Impacts: • Eye and lung irritation (but seldom > standard) • Acidic deposition of H2SO4. • Damage to limestone and concrete. • Sources: S in fuel is emitted as SO2 Source: Ref. (1)

13. Sulfur Dioxide Impacts: Acidic deposition of H2SO4. Pure water pH = 5.6 Source: Ref. (3)

14. Lead • Impacts: Brain and kidney damage. • Sources: Leaded gasoline was dominant, but Pb is no longer in U.S. on-road gasoline Source: Ref. (1)

15. Lead Impacts: Brain and kidney damage. Sources: Metals processing, battery mfr, etc Source: Ref. (1)

16. Greenhouse Gases Impacts: Global climate change Gases: Sources: See : Ref. (4)

17. The Greenhouse Effect What determines the average temperature of the earth?

18. The Greenhouse Effect What determines the average temperature of the earth? 1. Source: Ref. (5)

19. The Greenhouse Effect What determines the average temperature of the earth? 2.

20. The Greenhouse Effect What determines the average temperature of the earth? 3.

21. The Natural Greenhouse Effect • Average solar radiation in: 236 W per square m

22. The Natural Greenhouse Effect • Average solar radiation in: 236 W per square m • Without the atmosphere, temperature would be: -2 F

23. The Natural Greenhouse Effect • Average solar radiation in: 236 W per square m • Without the atmosphere, temperature would be: -2 F • Greenhouse effect of natural water and CO2: 148 W per square m (1 lightbulb every 2 feet) • Result: Average temperature = 57 F

24. The Human Contribution Source: Ref. (6)

25. The Human Contribution • Total effect until now: about 2.3 W / m2 (1 light bulb every 15 feet) • Predicted effect by 2050: Up to 7 W / m2 (1 light bulb every 9 feet)

26. What happens ifwe add 3 to 7 W / m2to the earth’s atmosphere?

27. Recent Trends in Temperature Source: Ref. (6)

28. Expected Impacts:More precip, more energy in weather • More extreme weather events are predicted • On average, more precipitation, but region-by-region, some will be wetter, some drier.

29. Long-term Impacts:Models predict changes in climate Two climate models predict Illinois climate in 2030 and 2090. Source: Ref. (7)

30. CO2 Emissions by Nation Developing nations will soon be the largest CO2 producers, but most CO2 in the atmosphere today came from to industrialized nations Source: Ref. (8)

31. Emissions by Sector CO2 Emissions by Nation Easiest mitigation measure = energy efficiency Household emissions See : Ref. (4)

32. Particulate Activities • Light scattering • Particles most effectively scatter light of wavelength ~ particle diameter. • Uncontrolled car exhaust scatters blue light. • Atmospheric gases also scatter, blue more than red. • Large concentrations of particle mixtures scatter all colors  white haze

33. Haze in Los Angeles Source: Ref. (9)

34. See Ref. (10) • Sky Blue, Sunset Red • Start with jar of clean water. • Demonstrate no scattering: • Shine light beam through – cannot see it from the sides, color at exit is white. • Add milk a little at a time • Observe effect on scattering: beam becomes visible, color at exit reddens, color from sides becomes bluish. • View an object through the jar: • Starts visible, becomes invisible: Haze. Particulate Activities

35. Sky Blue, Sunset Red Key points: • Why is the sky blue? • Why is the sunset red? • Why does the sunset get redder when there are fires or pollution? • Why are far-away objects invisible in smoggy places? Particulate Activities

36. See Ref. (10) • Air Strips • Obtain samples of particles and observe using magnifying glasses or microscopes. • Discuss local particle sources. Notes - Will only be able to see larger particles, like plant materials, dusts, or major smokes - Best to do during fall when more large particulates are in the air. Particulate Activities

37. Local Issues • Vehicle emissions • Sources of CO, CO2, particulates, NOx, VOCs • Strategies for reducing emissions • Fuel economy (all, proportional to fuel use) • Catalytic converters and no exhaust system leaks (CO, NOx, particulates, VOCs – no effect on CO2)

38. See Ref. (10) Local Issues • Vehicle emissions • Activity: Let’s Sock Car Exhaust • Use tube socks to collect particles from vehicle exhaust. • Notes: • Connect when vehicle is cold, run 5 min, let cool 5 min, remove, turn inside out. • Fuel is incompletely burned, and catalytic converters do not function, during 1st 5 minutes with cold engine. • Observe the socks outside (fuel on them)

39. Local Issues • Vehicle emissions • Activity: Let’s Sock Car Exhaust • Key points: • Emissions will relate directly to engine size (amount of fuel burned in 5 min). • Emissions will vary with age and maintenance. • Only particles are collected: CO, NOx, gaseous VOCs, CO2, water vapor are not.

40. Local Issues 2. Snowmobiles and wood stoves • Snowmobiles: 2-cycle engines are light, but of the C burned, • ~1/3 is fully burned and emitted as CO2. • ~1/3 is emitted as CO. • ~1/3 is not burned at all and released as gasoline.

41. Local Issues 2. Snowmobiles and wood stoves • Wood stoves: • Newer wood stoves have catalysts or secondary combustion; • those without emit more particles and VOCs • Can compare by viewing chimney exhaust (don’t be fooled by water fog) • Wood stoves can be a major source of indoor air pollution when smoke is pulled in from outdoors.

42. Local Issues 3. Indoor air pollution Key issues: • Radon • Molds • Particles and smokes

43. Local Issues 4. Atmospheric Dispersion • Radiative cooling on clear nights -> cold ground under warmer air. • Air flow over Lake Superior during summer -> cold water under warmer air.

44. The Effect of Temperature on Air MixingTemperature increasing with height

45. Warm Air over Cold Water Source: Ref (11)

46. Cold Air over Warm Water Source: Ref (11)

47. Lake SuperiorAverage Temperatures Percent Ice-free Source: Ref (12)

48. Fog forming over warm Portage Lake

49. Inversions over L.A. Source: Ref. (9)

50. Local Issues 5. Airborne pollutants and fishing advisories • PCBs: “PolyChlorinatedBiphenyls” • Chemically stable, thermally stable, high dielectric constants. • Used in transformers, as hydraulic fluids, …