1. Smog, Acid Deposition, Indoor and Outdoor Air Pollution
Secondary Pollutants
Smog, Acid Deposition, Indoor and Outdoor Air Pollution

2. Questions for Today What is Smog?
What is Acid Deposition and it’s effect on the environment?
What are sources for Indoor Air Pollution?
What are the methods to preventing Air Pollution?

3. URBAN OUTDOOR AIR POLLUTION
Industrial smog is a mixture of sulfur dioxide, droplets of sulfuric acid, and a variety of suspended solid particles emitted mostly by burning coal.
In most developed countries where coal and heavy oil is burned, industrial smog is not a problem due to reasonably good pollution control or with tall smokestacks that transfer the pollutant to rural areas. 3

4. Sunlight plus Cars Equals Photochemical Smog
Photochemical smog is a mixture of air pollutants formed by the reaction of nitrogen oxides and volatile organic hydrocarbons under the influence of sunlight. 4

5. Sunlight plus Cars Equals Photochemical Smog
Mexico City is one of the many cities in sunny, warm, dry climates with many motor vehicles that suffer from photochemical smog.
Figure 19-4 5

6. Factors Influencing Levels of Outdoor Air Pollution
Outdoor air pollution can be reduced by:
settling out, precipitation, sea spray, winds, and chemical reactions.
Outdoor air pollution can be increased by:
urban buildings (slow wind dispersal of pollutants), mountains (promote temperature inversions), and high temperatures (promote photochemical reactions). 6

7. Temperature Inversions
Cold, cloudy weather in a valley surrounded by mountains can trap air pollutants (left).
Areas with sunny climate, light winds, mountains on three sides and an ocean on the other (right) are susceptible to inversions.
Figure 19-5 7

8. Descending warm air mass Warmer air
Inversion layer
Inversion layer
Sea breeze
Increasing altitude
Figure 19.5
Natural capital degradation: two sets of topography and weather conditions that lead to prolonged temperature inversions, in which a warm air layer sits atop a cooler air layer. Air pollutants can build to harmful levels during an inversion. A temperature inversion can occur during cold, cloudy weather in a valley surrounded by mountains (left). Frequent and prolonged temperature inversions can also occur in an area with a sunny climate, light winds, mountains on three sides, and the ocean on the other (right). A layer of descending warm air from a high-pressure system prevents ocean-cooled air near the ground from ascending enough to disperse and dilute pollutants. Because of their topography, Los Angeles, California and Mexico City, Mexico (Figure 19-4) have frequent temperature inversions, many of them prolonged during the summer. QUESTION: Do you live in an area that suffers from fairly frequent thermal inversions?
Decreasing temperature
Fig. 19-5, p. 447 8

9. ACID DEPOSITION
Sulfur dioxides, nitrogen oxides, and particulates can react in the atmosphere to produce acidic chemicals that can travel long distances before returning to the earth’s surface.
Tall smokestacks reduce local air pollution but can increase regional air pollution. 9

10. ACID DEPOSITION
Acid deposition consists of rain, snow, dust, or gas with a pH lower than 5.6.
Figure 19-6 10

11. ACID DEPOSITION
pH measurements in relation to major coal-burning and industrial plants.
Figure 19-7 11

12. ACID DEPOSITION
Acid deposition contributes to chronic respiratory disease and can leach toxic metals (such as lead and mercury) from soils and rocks into acidic lakes used as sources for drinking water. 12

13. ACID DEPOSITION
Figure 19-8 13

14. ACID DEPOSITION
Air pollution is one of several interacting stresses that can damage, weaken, or kill trees and pollute surface and groundwater.
Figure 19-9 14

15. Emissions Lake Groundwater Acid deposition SO2 NOx H2O2 O3 PANs Others
Susceptibility to drought, extreme cold, insects, mosses, & disease organisms
Direct damage to leaves & bark
Reduced photo-synthesis and growth
Soil acidification
Tree death
Figure 19.9
Natural capital degradation: air pollution is one of several interacting stresses that can damage, weaken, or kill trees and pollute surface and groundwater.
Leaching of soil nutrients
Release of toxic metal ions
Root damage
Reduced nutrient & water uptake
Acids
Lake
Groundwater
Fig. 19-9, p. 451 15

16. Solutions Acid Deposition Prevention Cleanup
Reduce air pollution by improving energy efficiency
Add lime to neutralize acidified lakes
Reduce coal use
Add phosphate fertilizer to neutralize acidified lakes
Increase natural gas use
Increase use of renewable energy resources
Burn low-sulfur coal
Figure 19.10
Solutions: methods for reducing acid deposition and its damage. QUESTION: Which two of these solutions do you think are the most important?
Remove SO2 particulates & NOx from smokestack gases
Remove NOx from motor vehicular exhaust
Tax emissions of SO2
Fig , p. 452 16

17. INDOOR AIR POLLUTION
Indoor air pollution usually is a greater threat to human health than outdoor air pollution.
According to the EPA, the four most dangerous indoor air pollutants in developed countries are:
Tobacco smoke.
Formaldehyde.
Radioactive radon-222 gas.
Very small fine and ultrafine particles. 17

18. Tobacco Smoke Carbon Monoxide Methylene Chloride
Para-dichlorobenzene
Chloroform
Tetrachloroethylene
Formaldehyde
1, 1, 1-
Trichloroethane
Styrene
Nitrogen Oxides
Benzo-a-pyrene
Particulates
Tobacco Smoke
Radon-222
Asbestos
Carbon Monoxide
Methylene Chloride
Fig , p. 453 18

19. INDOOR AIR POLLUTION
Household dust mites that feed on human skin and dust, live in materials such as bedding and furniture fabrics.
Can cause asthma attacks and allergic reactions in some people.
Figure 19-12 19

20. HEALTH EFFECTS OF AIR POLLUTION
Normal human lungs (left) and the lungs of a person who died of emphysema (right).
Figure 19-15 20

21. Air Pollution is a Big Killer
Each year, air pollution prematurely kills about 3 million people, mostly from indoor air pollution in developing countries.
In the U.S., the EPA estimates that annual deaths related to indoor and outdoor air pollution range from 150,000 to 350,000.
According to the EPA, each year more than 125,000 Americans get cancer from breathing diesel fumes. 21

22. Air Pollution is a Big Killer
Spatial distribution of premature deaths from air pollution in the United States.
Figure 19-16 22

23. PREVENTING AND REDUCING AIR POLLUTION
The Clean Air Acts in the United States have greatly reduced outdoor air pollution from six major pollutants:
Carbon monoxide
Nitrogen oxides
Sulfur dioxides
Suspended particulate matter (less than PM-10) 23

24. Using the Marketplace to Reduce Outdoor Air Pollution
To help reduce SO2 emissions, the Clean Air Act authorized an emission trading (cap-and-trade) program.
Enables the 110 most polluting power plants to buy and sell SO2 pollution rights.
Between , the emission trading system reduced emissions.
In 2002, the EPA reported the cap-and-trade system produced less emission reductions than were projected. 24

25. Solutions: Reducing Outdoor Air Pollution
There are a of ways to prevent and control air pollution from coal-burning facilities.
Electrostatic precipitator: are used to attract negatively charged particles in a smokestack into a collector.
Wet scrubber: fine mists of water vapor trap particulates and convert them to a sludge that is collected and disposed of usually in a landfill. 25

26. Solutions: Reducing Outdoor Air Pollution
There are a # of ways to prevent and control air pollution from motor vehicles.
Because of the Clean Air Act, a new car today in the U.S. emits 75% less pollution than did pre-1970 cars.
There is and increase in motor vehicle use in developing countries and many have no pollution control devices and burn leaded gasoline. 26

27. Motor Vehicle Air Pollution
Solutions
Motor Vehicle Air Pollution
Prevention
Cleanup
Mass transit
Emission control devices
Bicycles and walking
Less polluting engines
Less polluting fuels
Car exhaust inspections twice a year
Improve fuel efficiency
Figure 19.19
Solutions: methods for reducing emissions from motor vehicles. Go to to find out how dirty your car is. QUESTION: Which two of these solutions do you think are the most important?
Get older, polluting cars off the road
Give buyers large tax write-offs or rebates for buying low-polluting, energy efficient vehicles
Stricter emission standards
Fig , p. 460 27

28. Indoor Air Pollution
Little effort has been devoted to reducing indoor air pollution even though it poses a much greater threat to human health than outdoor air pollution.
Environmental and health scientists call for us to focus on preventing air pollution (especially indoor) in developing countries. 28

29. Use adjustable fresh air vents for work spaces
Solutions
Indoor Air Pollution
Prevention
Cleanup or Dilution
Cover ceiling tiles & lining of AC ducts to prevent release of mineral fibers
Use adjustable fresh air vents for work spaces
Increase intake of outside air
Ban smoking or limit it to well ventilated areas
Change air more frequently
Set stricter formaldehyde emissions standards for carpet, furniture, and building materials
Circulate a building’s air through rooftop green houses
Figure 19.20
Solutions: ways to prevent and reduce indoor air pollution. QUESTION: Which two of these solutions do you think are the most important?
Prevent radon infiltration
Use exhaust hoods for stoves and appliances burning natural gas
Use office machines in well ventilated areas
Use less polluting substitutes for harmful cleaning agents, paints, and other products
Install efficient chimneys for wood-burning stoves
Fig , p. 461 29