1. Chapter 15
Air Pollution

2. HEALTH EFFECTS OF AIR POLLUTION
Normal human lungs (left) and the lungs of a person who died of emphysema (right).

3. Air Pollution is a Big Killer
Spatial distribution of premature deaths from air pollution in the United States.

4. Air Pollution Throughout the Earth
Air pollution is the introduction of chemicals, particulate matter, or microorganisms into the atmosphere in high enough concentrations to cause harm
Natural (fires, volcanoes) or anthropogenic (cars, factories)
It is part of a global system
There are many inputs (sources) and outputs (what removes the sources)
In developed countries, pollution has decreased due to policies and improved technology
6-major air pollutants

6. 6 Major Air Polluants
Compound and
Symbol
Human Derived
Sources
Effects/Impacts
Sulfur Dioxide
(SO2)
Combustion of
fossil fuels (mostly coal)
Respiratory irritant, harms plant tissue, creates sulfuric acid (harms aquatic ecosystems and some vegetation)
Nitrogen Oxides
(NOx)
Any combustion (car engines, lightning)
Respiratory irritant, photochemical smog, nitric acid (harms aquatic ecosystems)
Carbon Oxides
COx
Incomplete
Combustion (mostly ff)
Harms oxygen transport in bloodstream, causes headaches/death, global warming
Particulate Matter
Combustion,
construction
Harm respiratory and cardiovascular systems, premature death, haze
Lead (Pb)
Gas, coal, and
old paint
Impairs nervous system, learning disabilities
Ozone (O3)
Secondary component
(from a combination)
Exacerbates respiratory symptoms, damages plants

8. Primary and Secondary Pollutants
Primary pollutants are ones that are directly harmful from the source (smoke stack, exhaust pipe)
CO, CO2, SO2, NOx, VOCs, dust, microorganisms
Causes include factories, cars, wind and soil, volcanoes, forest fires, pollen, salt particles from the sea, etc.
Secondary pollutants are primary pollutants that have undergone transformation due to sunlight, water, oxygen, or other compounds
Ozone , acid rain
Harder to control
Point source pollution comes from a specific location
Nonpoint source pollution comes from many sources and is hard to trace back to its original source

10. Most suspended particles H2O2 O3 PANs
Primary Pollutants CO
CO2
Secondary Pollutants
SO2 NO
NO2
Most hydrocarbons
SO3
HNO3
H3SO4
Most suspended particles
H2O2 O3
PANs
Most NO3– and SO42– salts
Sources
Natural
Stationary
Mobile
Fig. 19-3, p. 442

11. Natural and Human Sources
Natural include volcanoes and fires (SOx, PM, CO, NOx), lightning (NOx), plants (VOCs), wind (dust)
Anthropogenic include on-road
vehicles, non-road equipment,
fires, wood combustion,
industrial processes, waste
disposal, fossil fuel combustion,
electricity generation
Temperature inversions (when
air gets warmer with height)
traps pollutants
Heat island

13. Smog Smog is an unhealthy mixture of air pollutants over urban areas
Industrial smog is a mixture of sulfur dioxide, droplets of sulfuric acid, and a variety of suspended solid particles emitted mostly by burning coal.
Photochemical smog is dominated by oxidants (ozone)
One of most difficult types of pollution to control
Occurs when UV energy reacts with chemicals
Los Angeles smog kills 3,900/year and costs $28 billion/year
Happens in cities that are warm, sunny, and dry
Smog is decreased by precipitation, salty sea spray, wind, and emissions reduction
Smog is increased by urban buildings, hills, high temps, and the grasshopper effect

14. Industrial smog
Photochemical smog

15. Acid Deposition
All rain is acidic, but not considered acid deposition unless pH is lower than 5.6
Formation
NOx and SO2 is released from natural and anthropogenic sources
In presence of oxygen and water, they become secondary pollutants through chemical reactions. Forms nitric acid (HNO3) an sulfuric acid (H2SO4)
Break down further to form nitrates, sulfates, and H+, which create the acid precipitation
Travel huge distances before falling in precipitation
Clean air act has reduced this greatly

16. Continued… Lower the pH of water bodies and reduce biodiversity
Release metals from the ground which are toxic to aquatic organisms
Nutrients leached from topsoil
Erode manmade structures
Respiratory problems
Build up of nitrogen and sulfur in soil

18. 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
Leaching of soil nutrients
Release of toxic metal ions
Root damage
Reduced nutrient & water uptake
Acids
Lake
Groundwater
Fig. 19-9, p. 451

20. 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
Remove SO2 particulates & NOx from smokestack gases
Remove NOx from motor vehicular exhaust
Tax emissions of SO2

21. Pollution Control
Use low sulfur coal and oil (more expensive), develop more efficient technologies, use less fuel…
Control of sulfur and NOx
Use fluidized bed combustion where coal is burned near calcium carbonate which absorbs ingredients and creates materials for wallboard
Cars use catalytic converters
Control of particulate matter
Let it settle with gravity, but than must dispose of ash
Filters allow gas through but not solids
Electrostatic precipitator charge particles so they stick together and then settle
Scrubbers use water and limestone that react with sulfur to produce gypsum (drywall)

23. Electrostatic Precipitator
Dirty gas
Dust discharge
Electrodes
Cleaned gas

24. Ozone Layer Ground level ozone is harmful, stratospheric is necessary
Protect us from UV radiation (blocks 95%)
Ozone destruction
Chlorofluorocarbons (CFCs) are organic compounds that add chlorine to the atmosphere
UV radiation breaks CFCs down into chlorine and carbon atoms
Chlorine breaks down the ozone bonds O3 + Cl  ClO + O2
In spring, UV radiation breaks the ClO apart and the free oxygen atom joins ClO + O  Cl + O2 (Cl is by itself)
Hole forms each spring over Antarctica

26. Hole over Antarctica
High-altitude polar stratospheric clouds form during the dark, frigid winter
Nitric acid in clouds splits chlorine off of CFCs
A polar vortex (swirling winds) traps chlorine
UV radiation in September (spring) sunshine dissipates the clouds and releases the chlorine
The chlorine destroys the ozone
December’s warmer air shuts down the polar vortex
Ozone-poor air diffuses, while ozone-rich air enters

27. Legislation
Air Pollution Control Act (1963) funded research and encouraged emissions standards
The Clean Air Act of 1970
Set standards for air quality, limits on emissions
Provided funds for pollution-control research
Allowed citizens to sue parties violating the standards
The Clean Air Act of 1990 strengthened regulations for auto emissions, toxic air pollutants, acidic deposition, stratospheric ozone depletion
Introduced emissions trading for sulfur dioxide

28. The Montreal Protocol
Montreal Protocol = 196 nations agreed to cut CFC production in half by 1998
Follow-up agreements deepened cuts, advanced timetables, and addressed other ozone-depleting chemicals
Industry shifted to safer, inexpensive, and efficient alternatives
Challenges still face us
CFCs will remain in the stratosphere for a long time
Nations can ask for exemptions to the ban

30. International agreements reduced ozone-depleting substances
The hole in the ozone has stopped growing

31. Using scientific notation
Anthropogenic chemicals are capable of destroying ozone in the stratosphere. One of the most threatening classes of man-made chemicals is cholorfluorocarbons, (CFCs). Chlorine enters the stratosphere through compounds known as chlorofluorocarbons (CFCs). CFC’s are a family of organic compounds whose properties make them ideal for use in refrigeration, air conditioning, and propellants in aerosol cans.
Unfortunately, scientists have discovered that one chlorine atom has the ability to breakdown and destroy as many as 100,000 ozone molecules before leaving the stratosphere.
Problem:
Suppose that 200 CFC molecules entered the stratosphere. If one chlorine atom destroys 100,000 ozone molecules, how many ozone molecules would be destroyed by 200 CFC molecules?
If the same number of CFC molecules entered the stratosphere each year for the next 30 years how many total ozone molecules would be destroyed?