1. Earth’s Changing Environment Lecture 2
Air Pollution
Lecture for ECE 2004, first day on air pollution. Gives an overview of the problem

2. Rachel Carlson. Silent Spring. DDT. Died 1964.
“Those who contemplate the beauty of the earth find reserves of strength that will endure as long as life lasts.”
- Rachel Carlson

3. The Atmosphere N2 780900 ppm (78.09%) O2 209400 ppm (20.94%)
Argon ppm (0.93 %)
CO ppm (0.037%)
Everything else is less than % or 30 ppm
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4. Layers of the Atmosphere
Stratosphere begins at about 10 miles above the surface.
Pressure drops with altitude.
So, less oxygen with altitude.

5. Air Pollution – Sources
Most air pollution is emitted from fixed and mobile sources at ground level.

6. Buoyant Force The density of air is proportional to its Temperature.
Hot polluted air is less dense than the cooler air around it.
So, hot polluted air will rise, expand, cool, and disperse

7. Temperature vs. Altitude
Hot air released at ground level will loose temperature as it rises and expands. The rate at which its temperature drops is the adiabatic lapse rate (ALR) and equals 3.5F per 1000 feet.
The environmental lapse rate (ELR) is typically equal to the ALR.

8. Unstable Air
If the ELR > ALR, then hot polluted air will rise and disperse.
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9. Temperature Inversion
If the there is a temperature inversion (a warm layer above the cool surface layer), the air will not rise.
This may lead to a severe pollution episode.
Temperature inversions are frequently caused by radiative cooling of the ground at night.

10. Subsidence Inversion
Descending air compresses and warms, creating an inversion layer

11. Global Air Circulation
The combination of air density, uneven solar heating, and the Earth’s rotation explains global air circulation and climate zones.

12. Hadley Cells

13. Pollutants Gases – CO, SOx, O3, NOx, and VOC
SPM (suspended particulate matter) – particulates and aerosols

14. Primary vs. Secondary

15. CO Primarily due to auto emissions.
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16. SO2 Primarily from power plants: coal and oil.
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17. VOC In rural areas, natural sources dominate.
In urban areas, transportation dominates.
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18. NOx Primarily from power plants and transportation
Emitted as NO and oxidized to NO2
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19. Particulates From Industry, power plants, and transportation
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20. Photochemical Smog Main harmful ingredient in smog is ozone.
Ozone is formed when UV radiation, high temperatures, Nitrogen oxides, and VOCs combine.
Automobiles are the main problem.
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21. Ozone Ozone is primarily a summer problem in the US.
Higher temperatures and higher ozone levels are need to drive the reactions.
VOCs have many sources.
NOx is primarily from cars.
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22. Acid Rain Acid rain is formed from SO2 and NO2 pollution.
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23. Acid Rain
Sulfuric acid (H2SO4) and nitric (HNO3) acid are formed and precipitated on vegetation in lakes and streams.
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24. pH
Normal rainwater is slightly acid because of carbonic acid (H2CO3) and nitric (HNO3). pH =5.6
pH values between 4.0 and 4.5 are common in NE, Canada, northern Europe
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25. Health Effects: Outdoor Air Pollution
Kills 200, ,000 annually globally.
Kills 20,000 people annually in US.
Particulates and ozone are the biggest problem
Major sources are coal-burning power plants and vehicle emissions
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26. Worse Air Pollution Disaster
London, England, 1952
From December 5 to 8, 1952
The meteorological conditions were ideal for a pollution. Anti-cyclonic or high pressure weather with stagnating continental polar air masses trapped under subsidence inversions produced a shallow mixing layer with an almost complete absence of vertical and horizontal air motion.
Fireplaces and industries supplied the hygroscopic condensation nuclei into the air to form dense fog.
Deaths from bronchitis increased by a factor of 10, influenza by 7, pneumonia by 5, tuberculosis by 4.5, other respiratory diseases by 6, heart diseases by 3 and lung cancer by 2.
4,000 Londoners perished.
London, England, 1953
From December 5 to 8, 1952, London experienced the worst air pollution disaster ever reported. The meteorological conditions were ideal for a pollution. Anti-cyclonic or high pressure weather with stagnating continental polar air masses trapped under subsidence inversions produced a shallow mixing layer with an almost complete absence of vertical and horizontal air motion. Fireplaces and industries supplied the hygroscopic condensation nuclei into the air to form dense fog. The daily temperatures were below the average. With such adverse conditions the concentrations of pollutants reached high values. With these adverse conditions, elderly people were particulary effected. Deaths from bronchitis increased by a factor of 10, influenza by 7, pneumonia by 5, tuberculosis by 4.5, other respiratory diseases by 6, heart diseases by 3 and lung cancer by 2. When a change in weather finally cleared the fog, 4,000 Londoners had perished in their "pea soup".
Pollution disasters with similarly high concentrations occurred in and again But the number of casualties during these disasters were less than that of 1952.

27. Health Effects: Indoor Air Pollution - Global
Kills 2.8 million annual globally
In developing countries, burning wood and other materials for heat and cooking is the major source.
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28. Health Effects: Indoor Air Pollution - US
Kills 100,000 people annually in US.
Cigarette smoke, formaldehyde, and radon-222 are primary indoor pollutants.
Intergovernment panel on Climate Changge