1. 6.3 Photochemical Smog

2. Types and Sources of Air Pollution
Air Pollution = gases, liquids, or solids present in the atmosphere in high enough levels to harm humans, other organisms, or materials.
Natural pollution (lightning causes forest fires, volcanic eruptions)
Human-induced pollution (ANTHROPOGENIC)
Harmful for 2 reasons:
They precipitate & settle on Earth
They alter the chemistry of the atmosphere
Much of the air pollution released by humans is concentrated in densely populated urban areas

3. Secondary Air Pollutants
Primary Air Pollutants
Harmful chemicals that enter directly into the atmosphere, often through burning fossil fuels. (or, natural)
EX: carbon oxides
nitrogen oxides
sulfur dioxide
particulate matter
unburned hydrocarbons
Secondary Air Pollutants
harmful chemicals that form from other substances that have been released into the atmosphere, often needing a photochemical reaction.
EX: tropospheric ozone PM
peroxyacetyl nitrate (PAN)
particulate matter
sulfur trioxide

4. Combustion Overview Question to ponder:
What burns in a candle... the wax, or the wick? Explain.
What is the WAX made of? What is the WICK made of?
Combustion is…
Combustion makes… CO / CO2 / HCs / NOx / SOx / PM

6. Primary Air Pollutants and Sources

7. Effects of Air Pollution
Class Discussion

8. Air Pollution & Human Health
Exposure to Low Levels causes…
Eye irritation
Inflammation of the respiratory tract
Immune system suppression
Development of emphysema & chronic bronchitis

10. PARTICULATE MATTER
smoke detector
filters
sticky materials
N & S & C OXIDES
devices / equipment
CO detector
chemical tests
AIR TOXICS
mold tests & filters
radon detectors
OZONE
Schoenbien papers
chemical tests
indirect evidence (plant growth, etc)
ozone action days
HYDROCARBONS
devices / equipment
ACID DEPOSITION
pH tests
indirect evidence

12. Smog… 1. Industrial Smog:
Air pollution that is localized in urban areas where it reduces visibility
1. Industrial Smog:
smoke pollution; principal pollutants are sulfur oxides and particulate matter. Worse in the winter months because of heating needs.

14. Formation of Tropospheric O3
HCs and NOx are emitted by fossil fuel combustion.
HCs – not all fuel is combusted.
Called VOCs – volatile organic compounds. Other Examples?
NOx – oxygen and nitrogen (from air) react in the high temps of combustion.
NO + O2 à NO2 (brown gas that contributes to urban haze)
NO2 + R à NO + O ...THEN... O + O2 à O3

15. Formation of Tropospheric O3
NO + O2 à NO2 (brown gas that contributes to urban haze)
NO2 + R à NO + O ...THEN... O + O2 à O3
Nitric Oxide (NO) reacts with Oxygen gas (O2) to form Nitrogen Dioxide (NO2).
NO2 is a brown gas that contributes to urban haze
NO2 absorbs sunlight and disassociates into NO & Oxygen atom.
Oxygen atom combines with oxygen molecules (O2) to form Ozone (O3).
Normally: most O3 oxidize NO back into NO2, creating a virtual cycle leading to only a very slight build-up of O3 at ground level.

16. Composition of Photochemical Smog

17. Summer & Winter Smog

18. Time of Day & Smog

19. Effects of Tropospheric Ozone
Oxidizing agent
Degrades building materials
Degrades rubber & plastics
Impacts car tire lifetime
Bleaches fabrics
Damage to plants / phytoplankton
Degrades chlorophyll (reduces photosynthetic ability and therefore productivity/crop yield ↓)
Damage to humans & animals
Reduces lung action (trouble breathing, aggravates asthma)
Decreased immune function
Eye/Nose/Throat irritation

20. Lets go see NYC…
….oops we cant!!

21. REVIEW…. What causes smog?

23. Topography and Air Pollution
Under normal conditions, air circulation patterns prevent toxic pollutants from increasing to dangerous levels near the ground.
That is not the case in this picture of LA…. What do you think is causing this to happen?

24. Temperature Inversions
AKA: Thermal Inversions
Air near the ground is cooler than the air at higher levels and the polluting gases/particulate matter remain trapped in high concentrations near the ground.

25. Los Angeles Located between coast and mountains
Sunny climate produces a layer of warm dry air at higher eleveations
Upwelling in the ocean produces cool ocean air
As cool air blows inland, the mountains block movement further and layer of warm dry air overlies cool air at the surface…. Temp inversion!!

27. Urban Heat Islands & Dust Domes
Urban Heat Island: air in urban areas is warmer than the air in the surrounding suburban and rural areas. Affects local air currents and weather conditions. Q: Why do they increase the number of thunderstorms???

28. Dust Domes: buildup of pollutants, especially particulate matter over cities. Convection of air lifts pollutants into the air where they remain because of somewhat stable air masses produced by urban heat island

29. CONTROLLING AIR POLLUTANTS
SCRUBBERS ELECTROSTATIC PRECIPITATORS

30. Clean Air Act of 1970
Authorized EPA to set limits on amounts of air pollutants permitted in the USA.
Most Dramatic Improvement?
98% decrease in atmospheric lead
Due to switch to unleaded gasoline
1990 Amendment:
Focused on Air Toxics & Motor Vehicle Emissions
Pre-1990: only 7 toxic chemicals regulated.
Post-1990: regulates 189 toxic chemicals.
1997 Amendment:
Limited emissions of PM-2.5 due to health concerns
Smaller PM can get deeper in lungs and lodge in alveoli, leading to many issues, including cancer.

31. What else can we do? Plant trees!
Public Transportation, carpool, bike/walk
Catalytic Converters on all cars
Removes NOx from vehicle emissions (lowering Acid Deposition)
Many LEDCs attribute much of their pollution to older cars without catalytic converters
Drive Smarter
Regular Tune-ups, keep tires properly inflated, drive the speed limit
SUVs emit nearly twice the pollution (different federal emissions standards)
Consider a hybrid or electric vehicle
Use small-engine machines correctly (ie: lawnmowers, leaf blowers, etc)
Up to 10% of US Hydrocarbon emissions
Not regulated the same way as vehicles, so emissions are higher
What time of day would be best to use them?
Be more like California! (consistently has stricter regulations than federal standards)
Use Scrubbers & Electrostatic Precipitators

32. Is the Clean Air Act working?

33. Indoor Air Pollution What are some types of indoor air pollution?
What are some sources of these pollutants?
What is the Sick Building Syndrome?

34. How Radon Infiltrates a House