1. Chapter 19 Air Pollution

2. Overview of Chapter 19 Atmosphere as a Resource
Types and Sources of Air Pollution
Effects of Air Pollution
Controlling Air Pollution in the US
Ozone Depletion in the Stratosphere
Acid Deposition
Air Pollution Around the World
Indoor Air Pollution

3. Atmosphere as a Resource
Atmospheric Composition
Nitrogen: 78.08%
Oxygen: 20.95%
Argon: 0.93%
Carbon dioxide: 0.04%
Ecosystem services
Blocks UV radiation
Moderates the climate
Redistributes water in the hydrologic cycle

4. Air Pollution - Terminology
Chemicals added to the atmosphere by natural events or human activities in high enough concentrations to be harmful
Two categories
Primary Air Pollutant
Harmful substance that is emitted directly into the atmosphere
Secondary Air Pollutant
Harmful substance formed in the atmosphere when a primary air pollutant reacts with substances normally found in the atmosphere or with other air pollutants, or with sunlight

5. Major Air Pollutants

7. Major Classes of Air Pollutants
Particulate Material
Nitrogen Oxides
Sulfur Oxides
Carbon Oxides
Hydrocarbons
Ozone

8. Particulate Material
Thousands of different solid or liquid particles suspended in air
Includes: soil particles, soot, lead, asbestos, sea salt, and sulfuric acid droplets
Dangerous
May contain materials with toxic/carcinogenic effects
Small particles can become lodged in lungs

9. Particulates Classification (2.5 vs. 10.0)
Pm 2.5 = combustion particles, metals, organic compounds of 2.5 microns and below
Pm 10.0 = larger solid particles (10 microns and above); Typically dust, pollen, mold, etc.

10. Nitrogen and Sulfur Oxides
Nitrogen Oxides
Gases produced by the chemical interactions between atmospheric nitrogen and oxygen at high temperature
Greenhouse gases that cause difficulty breathing
Sulfur Oxides
Gases produced by the chemical interactions between sulfur and oxygen
Causes acid precipitation

11. Carbon Oxides and Hydrocarbons
Gases carbon monoxide (CO) and carbon dioxide (CO2)
Greenhouse gases
Hydrocarbons (HC’s)
Diverse group of organic compounds that contain only hydrogen and carbon (ex: CH4- methane)
Some are related to photochemical smog and greenhouse gases

12. Ozone Tropospheric Ozone Stratospheric Ozone
Man- made pollutant in the lower atmosphere
Secondary air pollutant
Component of photochemical smog
Stratospheric Ozone
Essential component that screens out UV radiation in the upper atmosphere
Man-made pollutants (ex: CFCs) can destroy it

13. Ozone Damage to Grape Leaves

14. Primary Air Pollutants
NOTE: Ozone is a secondary air pollutant that can be indirectly measured by nitrogen oxides and volatile organics concentrations

15. Sources of Outdoor Air Pollution
Two main sources
Transportation
Industry
Intentional forest fires is also high

16. Urban Air Pollution Photochemical Smog (ex: Los Angeles below)
Brownish-orange haze formed by chemical reactions involving sunlight, nitrogen oxide, and hydrocarbons

17. Formation of Photochemical Smog

18. Sources of Smog in Los Angeles

19. Effects of Air Pollution
Low level exposure
Irritates eyes
Causes inflammation of respiratory tract
Can develop into chronic respiratory diseases

20. Children and Air Pollution
Greater health threat to children than adults
Air pollution can restrict lung development
Children breath more often than adults
Children who live in high ozone areas are more likely to develop asthma

21. Controlling Air Pollution
Smokestacks with electrostatic precipitator (right)
Without Electrostatic precipitator
With Electrostatic precipitator

22. Controlling Air Pollution
Smokestacks with scrubbers (right)
Particulate material can also be controlled by proper excavating techniques

23. Controlling Air Pollution
Gasoline vapors are a major source of VOC’s (volatile organic compounds), which are extremely harmful!
Phase I Vapor Recovery System for gasoline involves collecting unburned vapors from underground tanks at gas stations!

24. The Clean Air Act
Authorizes EPA to set limits on amount of specific air pollutants permitted
Focuses on 6 pollutants:
lead, particulate matter, sulfur dioxide, carbon monoxide, nitrogen oxides, and ozone
Act has led to decreases

25. The Clean Air Act

26. Urban Air Quality

27. Other Ways to Improve Air Quality
Reduce sulfur content in gasoline from its current average of 330 ppm to 30 ppm
Sulfur clogs catalytic converters
Require federal emission standards for all passenger vehicles
Including SUVs, trucks and minivans
Require emission testing for all vehicles
Including diesel

28. Ozone Depletion in Stratosphere
Ozone Protects earth from UV radiation

29. Stratospheric Ozone:
Ozone (O3) forms a layer in the stratosphere, measured in Dobson Units (typically 260 DU near the equator, higher toward the poles)
Ozone is created when UV radiation strikes molecules of Oxygen (O2) in the stratosphere, and splits (dissociates) them into free O atoms, which then quickly combine to form ozone.
O2 + UV -> O + O
O + O2 -> O3

30. Stratospheric Ozone:
Ozone can then be destroyed & reformed by the same UV radiation, in a natural cycle as follows:
O3 + UV -> O2 + O
O + O2 -> O3 as above
Ozone levels peak at about 25 KM above Earth’s surface.
Stratospheric Ozone – absorbs 99% of UV if left at “natural” levels

31. Three Categories of UV Radiation:
UV-C
UV-B
UV-A
Size of Wavelength: (nm)
Absorption:
Fully absorbed by O2 & O3
Most is absorbed by O3
Mostly reaches surface
Results Associated with Exposure:
Serious cell mutation, cancer
Skin cancer & cataracts, phytoplankton kills
Produces Vitamin D with background exposure levels

32. Ozone Depletion in Stratosphere
Ozone thinning/hole
First identified in 1985 over Antarctica
Caused by human-produced bromine and chlorine containing chemicals. (Halogens)
Ex: CFCs
propellants used for aerosol cans (no longer in use)
coolants in refrigeration (Freon)
foam (Styrofoam)
blowing agents in insulation
solvents

33. How does Chlorine (CFC) destroy Ozone?
Chemical reaction creates a catalyst!
CCl3F + UV Cl + CCl2F
Cl + O ClO + O2
ClO + O Cl + O2

34. Ozone Depletion in Stratosphere
“Hole” over Antarctica requires three conditions:
The development of the circumpolar vortex - a mass of frigid air that circulates around the southern polar region
The formation of polar stratospheric clouds – masses of ice crystals onto which Cl and Br can settle. This enables Cl and Br to destroy ozone
Sunlight just returning to polar region (occurs in spring in the S. hemisphere (Sept. – Oct.) which triggers the release of the Cl and Br from the polar stratospheric clouds

35. Effects of Ozone Depletion
Higher levels of UV-radiation hitting the earth
Eye cataracts
Skin cancer (right)
Weakened immunity
May disrupt ecosystems
May damage crops and forests

36. Recovery of Ozone Layer
Montreal Protocol (1987)
Reduction of CFCs
Started using HCFCs (greenhouse gas)
Phase out of all ozone destroying chemicals is underway globally
Satellite pictures in 2000 indicated that ozone layer was recovering
Full recovery will not occur until 2050 or later

37. Acid Deposition
Sulfur dioxide and nitrogen dioxide emissions react with water vapor in the atmosphere and form acids that return to the surface as either dry or wet deposition
pH scale

38. How Acid Deposition Develops

39. Effects of Acid Deposition
Declining Aquatic Animal Populations
Thin-shelled eggs prevent bird reproduction
Calcium is unavailable in acidic soil
Forest decline

40. Acid Deposition and Forest Decline

41. Air Pollution Around the World
Air quality is deteriorating rapidly in developing countries
Developing countries have older cars
Shenyang, China
Residents only see sunlight a few weeks each year
5 worst cities in world
Beijing, China;
Mexico City, Mexico;
Shanghai, China;
Tehran, Iran;
Calcutta, India

42. Case-In-Point Air Pollution in Beijing and Mexico City
Beijing (left)
Mexico City (above)

43. Long Distance Transport of Air Pollutants
Global Distillation Effect

44. Indoor Air Pollution Pollutants can be 5-100X greater than outdoors
Radon, cigarette smoke, carbon monoxide, nitrogen dioxide, formaldehyde pesticides, lead, cleaning solvents, ozone, and asbestos

46. Indoor Air Pollution - Radon