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Air Pollution
Chapter 18
What Is the Nature of the Atmosphere?
The atmosphere is structured in layers, including the troposphere, which supports life, and the stratosphere, which contains the protective ozone layer.
Troposphere – “Weather Breeder”
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
• Location – 11 – 30 miles up
What is Air Pollution and What Are the Major Outdoor Pollution Problems?
Air pollution – presence of chemicals in the atmosphere high enough to harm organisms, ecosystems or materials & to alter climate
Human (Anthropogenic) sources: mostly in industrialized and/or urban areas•Stationary sources – examples include industry and power plants•Mobile sources – examples include motor vehicles
Natural sources•Dust blown by wind•Pollutants from wildfires • and volcanoes•Volatile organics released • by plants •Withdrawing groundwater
Some Pollutants in the Atmosphere Combine to Form Other Pollutants
Primary pollutants – released directly into atmosphere
Secondary pollutants – formed by chemical reactions in air
What Are the Major Outdoor Air Pollutants?
Carbon oxides • Carbon monoxide (CO)
• Carbon dioxide (CO2)
• Sources - incomplete combustion of carbon-containing materials
• Human health and environmental impact
CO reduces ability of blood to transport O2
CO2 Do you need to ask? ;-)
Primary Pollutant
What Are the Major Outdoor Air Pollutants?
Nitrogen oxides (NO) and nitric acid (HNO3)
• Sources – automobile engines & coal burning power plants
• Human health and environmental impact – greenhouse gas, acid deposition, irritation to eyes, nose, aggravated asthma, etc
• Photochemical smog (makes harmful O3) – more later
Sulfur dioxide (SO2) and sulfuric acid (H2SO4)
• Sources – coal burning power plants & smelting• Human health and environmental impact – acid
deposition
What Are the Major Outdoor Air Pollutants?
Particulates• Suspended particulate matter (SPM)
• Sources – natural sources, plowed fields, construction, unpaved roads, tobacco smoke, coal burning power plants, cars
• Human health and environmental impact –
Irritate nose, throat, aggravate asthma, some can accumulate in body (lead, PCB’s)
What Are the Major Outdoor Air Pollutants?
Ozone (O3)
• Sources - photochemical smog• Human and environmental impact – same as
others, also damages plants, rubber in tires, etc.
Volatile organic compounds (VOCs)• Hydrocarbons, terpenes, methane• Sources – natural sources, landfills, solvents, rice
paddies, natural gas wells, etc.• Human and environmental impact – greenhouse
gas (CH4), damage plants, can cause cancer
Burning Coal Produces Industrial Smog
Chemical composition of industrial smog (grey)
Reduction of this smog in urban cities of the United States
China and smog• Human deaths
Sunlight Plus Cars Equals Photochemical Smog
Photochemical Smog• Chemical composition• Sources
VOCs + NO2 + Heat +
Sunlight yields • Ground level O3 and other
photochemical oxidants• Aldehydes• Other secondary pollutants
Human health and environmental impact
A Model of How Pollutants That Make Up Photochemicals Are Formed
Several Factors Can Decrease or Increase Outdoor Air Pollution
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
Outdoor air pollution may be increased by• Urban buildings• Hills and mountains• High temperatures• Emissions of VOCs from certain trees and plants • Grasshopper effect• Temperature inversions
A Temperature Inversion
What Is Acid Deposition and Why Is It a Problem?
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.
Acid Disposition Is a Serious Regional Air Pollution Problem
Acid deposition, acid rain• Formation• Local versus regional problems• Effects of prevailing winds• Buffers• Where is the worst acid deposition?
Natural Capital Degradation: Acid Deposition, Acid Rain
Current and Possible Future Acid Rain Problem Areas
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
Solutions: Acid Deposition, Prevention and Cleanup
What Are the Major Indoor Air Pollution Problems?
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.
Developing countries• Indoor burning• Poor suffer the greatest risk
Developed countries• Indoor air pollution is greater than outdoor air
pollution!!! WHY????
Indoor Air Pollution Is a Serious Problem
You asked WHY????....• 11 of the common air pollutants higher inside than outside• Greater in vehicles than outside• Health risks magnified: people spend 70–98% of their time is
indoors
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
Sources of these pollutants
Human health risks
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
Sick-building syndrome – Let’s watch TWC - SICK BUILDINGS!
Science: Sources and Paths of Entry for Indoor Radon-222 Gas
What Are the Health Effects of Air Pollution?
Air pollution can contribute to asthma, chronic bronchitis, emphysema, lung cancer, heart attack, and stroke.
Your Body’s Natural Defenses against Air Pollution Can Be Overwhelmed
Respiratory system protection from air pollutants• Role of cilia, mucus, sneezing, and coughing
Effect of smoking and prolonged air pollution exposure• Chronic bronchitis• Emphysema
Normal Human Lungs and the Lungs of a Person Who Died of Emphysema
Air Pollution Is a Big Killer
3 Million deaths per year world-wide• Mostly in Asia• Main causes
EPA: proposed stricter emission standards for diesel-powered vehicles
Link between international trade and air pollution• Cargo ships and pollution
Premature Deaths from Air Pollution in the U.S.
How Should We Deal with Air Pollution?
Legal, economic, and technological tools can help to clean up air pollution, but much greater emphasis should be focused on preventing air pollution. - SOUND FAMILIAR???
Laws and Regulations Can Reduce Outdoor Air Pollution
United States• Clean Air Acts: 1970, 1977, and 1990
EPA • National ambient air quality standards (NAAQs)
for 6 outdoor criteria pollutants• National emission standards for 188 hazardous
air pollutants (HAPs)• Toxic Release Inventory (TRI)
Laws and Regulations Can Reduce Outdoor Air Pollution
Good news in U.S.• Decrease in emissions• Use of low-sulfur diesel fuel• Cuts pollution
Developing countries• More air pollution
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
Solutions: Stationary Source Air Pollution
Solutions: Motor Vehicle Air Pollution, Prevention and Cleanup
Solutions: Indoor Pollution, Prevention and Cleanup or Dilution