Air Pollution

1
Chapter 17

• Air Pollution
• Natural Sources
• Volcanoes
• Deserts
• Decomposition
• Human Sources
• Auto Emissions
• Power Plant Emissions
• Chemical Plant Emissions
• The Difference
• Human Sources can be controlled and prevented,
  natural sources cannot.

2
Chapter 17

• Why is Air Pollution a Concern?
• Gravity tends to hold denser gasses close to
  Earths surface, many pollutants are fairly dense
  so
• Well known examples of deadly episodes
• London, Eng 4000 killed
• Donora, PA 17 killed 5900 sick
• Chronic Issues, too
• Mexico City 6400 death each year

3
Chapter 17

• Primary Air Pollutants 5 types
• Carbon Monoxide (CO)
• Causesincomplete combustion of gas, coal, wood
  trash, etc
• Largest source is Automobile
• 2nd Largest Tobacco Smoke
• Small concentrations can result in death
• 0.001 for several hours is enough
• Not persistent
• HydroCarbons
• Causesincomplete combustion, evaporation from
  fuelautomobiles, refineries, industries.
• Engine modifications help

4
Chapter 17

• Particulates lt10 microns
• Very small pieces of solids
• Causesparticles from fire, asbestos from brakes,
  dust/ash from industry
• Aesthetic/Cancer Causing
• Accumulate or carrier
• Sulfur Dioxide (SO2)
• Causesburning of fossil fuels with S
• Irritate lungs and forms acids when mixed
• 1306 London banned use of S rich coals
• 1952 inversion of S rich air poll. kills 4000

5
Chapter 17

• Oxides of Nitrogen (NOx, NO, NO2)
• Causesautomobile
• Catalytic converters help
• Involved in production of Photochemical Smog
• Secondary Air Pollutants
• Photochemical Smog
• Interaction of NOx with UV light
• Results in ground level ozone
• Usually reddish-brown haze

6
Chapter 17

• Ground Level Ozone formation
• Rush hour N2 O2 -gt 2NO
• atmospheric O2 2NOO2 -gt 2NO2
• UV light NO2 UV -gtNO O
• atmospheric O2 O2 O -gt O3
• Ozone is oxidizer and highly reactive
• Reacts with living tissue
• Lungs
• Chlorophyll in plants
• Geography and climate influence formation
• Valley ringed by mountainbad
• Solutionget rid of IC cars or move city

7
Chapter 17

• Other air pollutants
• Lead
• Toxics
• Radon
• Control of Air Pollution
• Solutions depend on willingness of governments,
  industry and individuals to make changes
• Pollution control in cars
• Particulates
• SOx

8
Chapter 17

• The Clean Air Act (1967, rev 70,77, 90)
• 4 Categories of programs
• 1. All new/existing sources are subject to
  ambient air quality regs.
• 2. New sources subject to more stringent control
  technology and permitting
• 3. Control of specific pollution problems
  including haz. Air emissions and visisbility
  impairment
• 4. Comprehensive permit program
• Air quality standards for SO2, NOx, particulates,
  CO, O3, and lead
• State responsibility for implementing SIPs

9
Chapter 17

• The Clean Air Act (contd)
• Ways to go but program has been successful
• Emissions of 6 worst pollutants down 33
• Benefits outweigh costs by 40 to 1
• Still, smog may affect 6 million asthmatics and
  may send 160,000 people to emergency room each
  year

10
Chapter 17

• Acid Rain
• Acid deposition can be natural or man-made
• Volcanoes, vegetation, lightning
• Coal burning, automobiles
• Can be wet or dry
• Wet with rain or snow
• Dry with settling of particles
• All processes called ACID RAIN
• Effects
• Aesthetics on buildings/monuments
• Forests, aquatic ecosystems, soil, etc
• Not as big an issue in Texas as NE US and Canada

11
Chapter 17

• Global Warming
• Lots of unknowns but many agree it is potential
  future reality with human causes
• How does it work?
• Greenhouse gasses allow sunlight to pass through
  but reflect/absorb resulting heat energy from
  earth.
• CO2 is most abundant GH gas
• Increase from 315 ppm to 362 ppm in 40 years
• Can counter with increases in energy efficiency
  and uptake/sequestration.

12
Chapter 17

• Global Warming (contd)
• Chlorofluorocarbons (CFC)
• Small amounts released but highly effective
• 15,000 times that of CO2
• Banned for most part in US, Canada, Europe
• Releases are expected to continue to decline
• Major effects on ozone layer
• Methane and NO
• Also involved in global warming but limited
  ability to control releases

13
Chapter 17

• Effects of Global Warming
• Worsening Health Effects
• Exacerbate smog/ground level ozone
• More disease/wider range of disease/vectors
• More heat more heart attacks etc
• Rising Sea Level
• Loss of coastal land
• More flooding
• Disruption of Water Cycle
• Greater Droughts/Floods
• Changing Forests and Natural Areas
• Range Shifts by 300 miles
• Change in composition

14
Chapter 17

• Effects of Global Warming (contd)
• Challenges to Agriculture/Food Supply
• May increase yields in some areas
• Increase irrigation demand too
• Can likely cope with changes
• Many unknown effects
• Feedback loops on global cycle?
• Politics and Economics will ultimately decide our
  contribution to reduce global warming

15
Chapter 17

• Ozone Depletion
• Ozone is O3
• Absorbs harmful effects of UV radiation high up
  in atmosphere
• 99 of UV light is prevented from reaching earth
• Prevents cancer, cataracts and mutations
• CFCs destroy ozone and prevent reforming
• 20-30 yrs to reach upper atmosphere
• Can react for up to 120 yrs
• Ozone depletion will worsen well into next
  century based on prior releases