air pollution chapter 18. the asian brown cloud 18-1 what is the nature of the atmosphere? concept...
TRANSCRIPT
Air Pollution
Chapter 18
The Asian Brown Cloud
18-1 What Is the Nature of the Atmosphere?
Concept 18-1 The atmosphere is structured in layers, including the troposphere, which supports life, and the stratosphere, which contains the protective ozone layer.
Air Movements in the Troposphere Play a Key Role in Earth’s Weather and Climate
Troposphere • 75–80% of the earth’s air mass• Closet to the earth's surface• Chemical composition of air• Rising and falling air currents: weather and
climate• Involved in chemical cycling
The Stratosphere Is Our Global Sunscreen
Stratosphere• Similar composition to the troposphere, with 2
exceptions• Much less water
• O3, ozone layer, filters UV
Fig. 18-3, p. 470
Atmospheric pressure (millibars)
120
Temperature
750 200 400 600 800 1,000
110
Thermosphere 65100
90Mesopause 55
80
70Mesosphere 45
60 Stratopause35
50
Alt
itu
de
(m
iles
)
Alt
itu
de
(ki
lom
eter
s)
40
25Stratosphere
30 Tropopause
20 Ozone layer15
10 Pressure Troposphere 5
(Sea level)
0
–80 –40 0 40 80 120Temperature (˚C)
Pressure = 1,000 millibars at ground level
18-2 What Are the Major Outdoor Pollution Problems?
Concept 18-2 Pollutants mix in the air to form industrial smog, mostly the result of burning coal, and photochemical smog, caused by motor vehicle, industrial, and power plant emissions.
Air Pollution Comes from Natural and Human Sources
Natural sources• Dust blown by wind• Pollutants from wildfires and volcanoes• Volatile organics released by plants
Human sources: mostly in industrialized and/or urban areas• Stationary sources• Mobile sources
Fig. 18-4, p. 472
Primary Pollutants
CO CO2Secondary Pollutants
SO2 NO NO2
Most hydrocarbons SO3
Most suspended particles HNO3 H2SO4
H2O2 O3 PANs
Sources Natural Stationary
Mobile
Most NO3− and SO4
2− salts
Chemical Reactions That Form Major Outdoor Air Pollutants
Major Air Pollutants
• Carbon oxides: – Carbon monoxide (CO) is a highly toxic gas that
forms during the incomplete combustion of carbon-containing materials.
– 93% of carbon dioxide (CO2) in the troposphere occurs as a result of the carbon cycle.
– 7% of CO2 in the troposphere occurs as a result of human activities (mostly burning fossil fuels).
• It is not regulated as a pollutant under the U.S. Clean Air Act.
CO trends
Major Air Pollutants
• Nitrogen oxides and nitric acid: – Nitrogen oxide (NO) forms when nitrogen and oxygen
gas in air react at the high-combustion temperatures in automobile engines and coal-burning plants. NO can also form from lightening and certain soil bacteria.
– NO reacts with air to form NO2. NOx form PANs.
– NO2 reacts with water vapor in the air to form nitric acid (HNO3) and nitrate salts (NO3
-) which are components of acid deposition.
Sources NOx
Click for more NOx source information
NOx Trends
Major Air Pollutants
• Sulfur dioxide (SO2) and sulfuric acid:
– About one-third of SO2 in the troposphere occurs naturally through the sulfur cycle.
– Two-thirds come from human sources, mostly combustion (S+ O2 SO2) of sulfur-containing coal and from oil refining and smelting of sulfide ores.
– SO2 in the atmosphere can be converted to sulfuric acid (H2SO4) and sulfate salts (SO4
2-) that return to earth as a component of acid deposition.
Sources SOx
Click for more SOx source information
SO2 Trends
Major Air Pollutants
• Suspended particulate matter (SPM):– Consists of a variety of solid particles and liquid
droplets small and light enough to remain suspended in the air.
– The most harmful forms of SPM are fine particles (PM-10, with an average diameter < 10 micrometers) and ultrafine particles (PM-2.5).
– According to the EPA, SPM is responsible for about 60,000 premature deaths a year in the U.S.
Sources Particulate Matter
Click for more PM source information
PM-10 trends
PM-2.5 trends
Major Air Pollutants
• Ozone (O3):
– Is a highly reactive gas that is a major component of photochemical smog.
– It can • Cause and aggravate respiratory illness.• Can aggravate heart disease.• Damage plants, rubber in tires, fabrics, and paints.
Ventura County Ozone Trends
Click for Ventura County Air Pollution Control District
South Coast Air Basin Ozone Trend
Click here of California Air Resource Board
Major Air Pollutants
• Volatile organic compounds (VOCs):– Most are hydorcarbons emitted by the leaves of many
plants and methane.– About two thirds of global methane emissions comes
from human sources.– Other VOCs include industrial solvents such as
trichlorethylene (TCE), benzene, and vinyl chloride.• Long-term exposure to benzene can cause cancer,
blood disorders, and immune system damage.
Fig. 18-7, p. 476
SOLUTIONSLead Poisoning
Prevention ControlPhase out leaded gasoline worldwide
Replace lead pipes and plumbing fixtures containing lead solder
Phase out waste incineration
Remove leaded paint and lead dust from older houses and apartments
Ban use of lead solder
Sharply reduce lead emissions from incinerators
Ban use of lead in computer and TV monitors
Remove lead from TV sets and computer monitors before incineration or land disposal
Ban lead glazing for ceramicware used to serve food
Test for lead in existing ceramicware used to serve food
Ban candles with lead cores
Test existing candles for lead
Test blood for lead by age 1
Wash fresh fruits and vegetables
How Pollutants Are Formed from Burning Coal and Oil, Leading to Industrial Smog
Fig 18-8
A Model of How Pollutants That Make Up Photochemicals Are Formed
Fig 18-9
Animation: Formation of photochemical smog
Global Outlook: Photochemical Smog in Santiago, Chile
Several Factors Can Decrease or Increase Outdoor Air Pollution (1)
Outdoor air pollution may be decreased by• Settling of particles due to gravity• Rain and snow• Salty sea spray from the ocean• Winds • Chemical reactions
Several Factors Can Decrease or Increase Outdoor Air Pollution (2)
Outdoor air pollution may be increased by• Urban buildings• Hills and mountains• High temperatures• Emissions of VOCs from certain trees and plants • Grasshopper effect – wind transports from
tropics/temperate to polar areas• Temperature inversions
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 18-11Figure 18-11
18-3 What Is Acid Deposition and Why Is It a Problem?
Concept 18-3 Acid deposition is caused mainly by coal-burning power plant and motor vehicle emissions, and in some regions, threatens human health, aquatic life and ecosystems, forests, and human-built structures.
Natural Capital Degradation: Acid Deposition, Acid Rain
Fig 18-12
ACID DEPOSITION
pH measurements in relation to major coal-burning and industrial plants.
Figure 19-7Figure 19-7
Current and Possible Future Acid Rain Problem Areas
Fig 18-13
Acid Deposition Has a Number of Harmful Effects
Human respiratory disorders Aquatic ecosystems affected Release of toxic metals Leaching of soil nutrients Loss of crops and trees Damage to buildings, statues, and monuments
Statue Corroded by Acid Deposition and Other Forms of Air Pollution, RI, U.S.
Natural Capital Degradation: Air Pollution Damage to Trees in North Carolina, U.S.
Fig18-14
Fig. 18-15, p. 483
SOLUTIONS
Acid Deposition
Prevention CleanupAdd lime to neutralize acidified lakes
Reduce coal use
Burn low-sulfur coal
Add phosphate fertilizer to neutralize acidified lakes
Increase natural gas use
Increase use of renewable energy resources
Remove SO2 particulates and NOx from smokestack gasesRemove NOx from motor vehicular exhaust
Tax emissions of SO2
Reduce air pollution by improving energy efficiency
Active Figure: Effect of air pollution in forests
18-4 What Are the Major Indoor Air Pollution Problems?
Concept 18-4 The most threatening indoor air pollutants are smoke and soot from wood and coal cooking fires (a hazard found mostly in developing countries) and chemicals used in building materials and products.
Indoor Air Pollution Is a Serious Problem
Who are at greatest risk from indoor air pollution?• Children under 5 and the elderly• Sick• Pregnant women• People with respiratory disorders or heart
problems• Smokers• Factory workers
Indoor Air Pollution Is a Serious Problem
Four most dangerous indoor air pollutants• Tobacco smoke• Formaldehyde• Radioactive radon-222 gas• Very small particles
Indoor Air Pollution Is a Serious Problem
Other possible indoor air pollutants• Pesticide residue• Pb particles• Living organisms and their excrements• E.g., Dust mites and cockroach droppings
• Airborne spores of molds and mildews
Fig. 18-16, p. 484
Source: Chlorine-treated water in hot showers Possible threat: Cancer
Source: Air fresheners, mothball crystals Threat: Cancer
Source: Dry-cleaning fluid fumes on clothes Threat: Nerve disorders, damage to liver and kidneys, possible cancer
Source: Aerosol sprays Threat: Dizziness, irregular breathing
1,1,1-Trichloroethane
Source: Furniture stuffing, paneling, particleboard, foam insulation Threat: Irritation of eyes, throat, skin, and lungs; nausea; dizziness
Formaldehyde
Styrene
Nitrogen oxides Source: Carpets, plastic products Threat: Kidney and liver damage
Source: Unvented gas stoves and kerosene heaters, woodstoves Threat: Irritated lungs, children's colds, headaches
Source: Tobacco smoke, woodstoves Threat: Lung cancer
Benzo- α -pyrene
Particulates
Source: Pollen, pet dander, dust mites, cooking smoke particles Threat: Irritated lungs, asthma attacks, itchy eyes, runny nose, lung disease
Source: Radioactive soil and rock surrounding foundation, water supply Threat: Lung cancer
Radon-222
Tobacco smokeSource: Cigarettes Threat: Lung cancer, respiratory ailments, heart disease
Asbestos Carbon monoxide Methylene chlorideSource: Pipe insulation, vinyl ceiling and floor tiles Threat: Lung disease, lung cancer
Source: Faulty furnaces, unvented gas stoves and kerosene heaters, woodstoves Threat: Headaches, drowsiness, irregular heartbeat, death
Source: Paint strippers and thinners Threat: Nerve disorders, diabetes
Chloroform Para-dichlorobenzene Tetrachloroethylene
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.
Case Study: Radioactive Radon
• Radon-222, a radioactive gas found in some soils and rocks, can seep into some houses and increase the risk of lung cancer.
Sources and paths of entry Sources and paths of entry for indoor radon-222 gasfor indoor radon-222 gas.
Figure 18-18Figure 18-18
18-5 What Are the Health Effects of Air Pollution?
Concept 18-5 Air pollution can contribute to asthma, chronic bronchitis, emphysema, lung cancer, heart attack, and stroke.
Premature Deaths from Air Pollution in the U.S.
18-6 How Should We Deal with Air Pollution?
Concept 18-6 Legal, economic, and technological tools can help to clean up air pollution, but much greater emphasis should be focused on preventing air pollution.
PREVENTING AND REDUCING AIR POLLUTION
Environmental scientists point out several deficiencies in the Clean Air Act:• The U.S. continues to rely on cleanup rather than
prevention.• The U.S. Congress has failed to increase fuel-
efficiency standards for automobiles.• Regulation of emissions from motorcycles and
two-cycle engines remains inadequate.• There is little or no regulation of air pollution from
oceangoing ships in American ports.
PREVENTING AND REDUCING AIR POLLUTION
• Airports are exempt from many air pollution regulations.
• The Act does not regulate the greenhouse gas CO2.
• The Act has failed to deal seriously with indoor air pollution.
• There is a need for better enforcement of the Clean Air Act.
We Can Use the Marketplace to Reduce Outdoor Air Pollution
Emission trading or cap-and-trade program• Mixed reactions to program
• SO2 emissions down significantly
• NO2 will be tried in the future
EPA cap and trade for acid rain report
California ARB on greenhouse gas cap and trade
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.
Electrostatic Precipitator
Can remove 99% of particulate matter
Does not remove hazardous ultrafine particles.
Produces toxic dust that must be safely disposed of.
Uses large amounts of electricity
Wet Scrubber
Can remove 98% of SO2 and particulate matter.
Not very effective in removing hazardous fine and ultrafine particles.
Integrated Gasification Combined-Cycle (IGCC) systems
Gasifier uses heat and pressure to break apart“feedstock” to produce “syngas” (hydrogen and CO)
Click for DOE information on gasification
Fig. 18-22, p. 491
SOLUTIONS
Stationary Source Air Pollution
Prevention
Burn low-sulfur coalDisperse emissions above thermal inversion layer with tall smokestacksRemove sulfur from
coal
Remove pollutants after combustionConvert coal to a
liquid or gaseous fuel
Shift to less polluting energy sources
Tax each unit of pollution produced
Dispersion or Cleanup
Fig. 18-23, p. 491
SOLUTIONS
Motor Vehicle Air Pollution
Prevention CleanupUse mass transit Require
emission control devicesWalk or bike
Use less polluting fuels
Improve fuel efficiency
Inspect car exhaust systems twice a year
Get older, polluting cars off the road
Give large tax write- offs or rebates for buying low-polluting, energy efficient vehicles
Set strict emission standards
Fig. 18-24, p. 492
SOLUTIONSIndoor Air Pollution
Prevention Cleanup or DilutionClean ceiling tiles and line AC ducts to prevent release of mineral fibers
Use adjustable fresh air vents for work spaces
Ban smoking or limit it to well-ventilated areas Increase intake of outside
air
Change air more frequently
Set stricter formaldehyde emissions standards for carpet, furniture, and building materials Circulate a building’s air
through rooftop greenhousesPrevent radon
infiltration
Use efficient venting systems for wood-burning stoves
Use office machines in well-ventilated areas
Use less polluting substitutes for harmful cleaning agents, paints, and other products
Use exhaust hoods for stoves and appliances burning natural gas
What Can You Do? Indoor Pollution: Ways to Reduce Your Exposure
Fig. 18-26, p. 493
SOLUTIONS
Air Pollution
Outdoor IndoorImprove energy efficiency to reduce fossil fuel use
Reduce poverty
Distribute cheap and efficient cookstoves or solar cookers to poor families in developing countries
Rely more on lower-polluting natural gas
Rely more on renewable energy (especially solar cells, wind, and solar-produced hydrogen)
Reduce or ban indoor smoking
Transfer energy efficiency, renewable energy, and pollution prevention technologies to developing countries
Develop simple and cheap tests for indoor pollutants such as particulates, radon, and formaldehyde