Chapter 17 Air and Air Pollution

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Chapter 17Air and Air Pollution
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The Atmosphere

• Atmosphere- a sea of air above the earths
  surface with several spherical layerse
• Each layer has different changes in temperature
  the result of differences in the absorption of
  incoming solar energy
• Consists of two gases nitrogen (78) and oxygen
  (21) The remainder is water vapor, argon, carbon
  dioxide, and trace amounts of several other gases
• Troposphere contains 75 80 of the mass of
  the earths air
• Extends 17 km above sea level at the equator and
  about 8 km over the poles

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The Stratosphere

• Stratosphere the atmospheres second layer
  which extends from 17 48 km above the earths
  surface
• Volume of water vapor is less concentration of
  ozone is much higher.
• Stratospheric ozone is produced when some of the
  oxygen molecules there interact with ultraviolet
  (UV) radiation emitted by the sun. Keeps about
  95 of the UV rays from reaching earths surface,
  
• Allows humans and other forms of life to exist on
  land.
• Helps protect us from sunburn, skin and eye
  cancer, cataracts, and damage to the immune
  system
• Prevents the oxygen in the atmosphere from
  turning into ozone, a harmful pollutant

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Air Pollution Basics

• Air Pollution the presence of one or more
  chemicals in the atmosphere in sufficient
  quantities and duration to 1) cause harm to us
  and other forms of life 2)alter climate
• Can come from both natural sources and human
  activities
• Natural sources
• Dust from windstorms and soil
• Sulfur oxides and particulate matter from
  volcanoes
• Carbon oxides, nitrogen oxides, and particulates
  from forest fires
• Hydrocarbons and pollen from live plants
• Methane and hydrogen sulfide from decaying plants
• Salt particulates from the sea
• ? Most are spread out and rarely reach harmful
  levels

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Primary Vs.Secondary

• Primary Pollutants those emitted directly into
  the troposphere in a potentially harmful form
• Secondary Pollutants when primary pollutants
  react with one another or with the basic
  components of air to form new pollutants
• Cities have higher pollution levels than rural
  areas winds can spread long-lived primary and
  secondary air pollutants emitted in urban and
  industrial areas to the countryside and other
  downwind urban areas

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Photochemical Smog

• Photochemical Smog a mixture of air pollutants
  produced in the lower atmosphere by the reaction
  of hydrocarbons and nitrogen oxides under the
  influence of sunlight. Especially harmful
  components include ozone, PANs (peroxyacyl
  nitrates), and various aldehydes

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Industrial Smog

• Industrial Smog - types of air pollution
  consisting mostly of a mixture of sulfur dioxide,
  suspended droplets of sulfuric acid formed from
  some of the sulfur dioxide, and a variety of
  suspended solid particles

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Factors Influencing Smog

• Frequencies and severity of smog in an area
  depends on
• Local climate and topography
• Population density
• The amount of industry
• The fuels used in industry, heating, and
  transportation

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Air Pollution Can Be Reduced/Increased By

• Air Pollution can be reduced by
• Rain and snow help clean the air of pollutants
• Winds help sweep pollutants away, dilutes
  pollutants by mixing them with cleaner air, and
  bring in fresh air (deposited elsewhere)
• Air Pollution can be increased by
• Urban buildings can slow wind speeds and reduce
  dilution and removal of pollutants
• Hills and mountains - tend to reduce the flow of
  air in valleys below them and allow pollutant
  levels to build up at ground level
• High temperatures which promote the chemical
  reactions leading to photochemical smog formation

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Temperature Inversion

• Temperature Inversion a layer of warm air can
  lie atop a layer of cooler air nearer the ground
  cooler air is denser and does not rise and mix
  with the air above it. Pollutants can concentrate
  in the layer of cool air near the ground.
• Subsidence Temperature Inversion occurs when a
  large mass of warm air moves into a region at
  high altitude and floats over a mass of colder
  air near the ground. Keeps the air over the city
  and prevents mixing and dispersion of air
  pollution
• Radiation Temperature Inversion typically
  occurs at night as the air near the ground cools
  faster than the air above it. As the sun rises
  and warms the earths surface, a radiation
  inversion normally disappears by noon and
  disperses the pollution built up during the
  night.

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Acid Deposition

• Primary pollutants can be transported far away by
  winds and in the process collect secondary
  pollutants such as 1) nitric acid vapor 2)
  droplets of sulfuric acid 3) particles of
  acid-forming sulfate and nitric salt
• These acidic substances remain in the atmosphere
  for 2 14 days, depending mostly on prevailing
  winds, precipitation, and other weather patterns.
• They can descend to the earths surface in two
  forms (Acid Deposition Acid Rain)
• Wet deposition as acidic rain, snow, fog, and
  cloud vapor with a pH less than 5.6
• Dry deposition as acidic particle

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Areas Most Affected

• Acid deposition is a regional problem in the
  eastern US and in other parts of the world.
• pH of rain in the US is 4.2 4.7 10 times more
  the acidity of natural precipitation with a pH of
  5.6
• Some of the soil contains calcium carbonate or
  limestone that can neutralize, or buffer, some
  inputs of acid.
• Areas most sensitive to acid deposition are
• Those with thin acidic soils made from granite
  rock without natural buffering
• Those in which the buffering capacity of soils
  has been depleted by decades of acid deposition.
• The worst acid deposition is in Asia, especially
  in China

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Effects of Acid Deposition

• Contributes to human respiratory disease
• Can leach toxic chemicals such as lead and copper
  from water pipes into drinking water
• Damages statues, buildings, metals, and car
  finishes
• Decreased atmospheric visibility
• Can lower profits and cause job losses because of
  lower productively in fisheries, forests, and
  farms.

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Effects of Acid Deposition on Aquatic Ecosystems

• Effects when the pH falls below 6 and especially
  below 5
• Loss of all fish populations below a pH of 4.5
• Release of aluminum ions attached to minerals in
  nearby soil into lakes stimulates excessive
  mucus formation which asphyxiates the fish
• Mostly happens in areas with little buffering
  capacity results in acid shock
• Caused by the runoff of large amounts of highly
  acidic water and aluminum ions into lakes and
  streams

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Effects of Acid Deposition on Plants and Soil
Chemistry

• Acid deposition can harm forests and crops,
  especially when the soil pH falls below 5.1
• Can damage leaves and needles
• Can leach essential plant nutrients from soils
  which reduces the plants productivity and ability
  of the soils to buffer
• Release aluminum ions, which can hinder uptake
  and use of soil nutrients and water by plants
• Can dissolve insoluble soil compounds and
  releasing ions of metals such as lead, cadmium,
  and mercury that can be absorbed by plants and
  are highly toxic to plants and animals
• Promoting the growth of acid-loving mosses that
  can kill trees
• Weaken trees and other plans so they become more
  susceptible to other types of damage such as
  severe cold, diseases, insect attacks, drought,
  and harmful mosses

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What Can Be Done To Reduce Acid Deposition

• Preventative approaches
• Reduce air pollution by improving energy
  efficiency
• Reduce coal use
• Increase natural gas use
• Increase use of renewable energy resources
• Burn low-sulfur coal
• Remove SO2 particulates and NO from smokestack
  gases
• Remove NO from motor vehicle exhaust
• Tax emission of SO2
• Cleanup
• Add lime to neutralize acidified lakes would
  cost 8 billion per year
• Add phosphate fertilizer to neutralize acidified
  lakes

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Acid Deposition Conflict

• Controlling Acid Deposition The Political
  Problem
• The people and ecosystems it affects often are
  quite distant from those who cause the problem
• Countries with large supplies of coal have a
  strong incentive to use it as a major energy
  resource
• Owners of coal-burning power plants say the costs
  of adding equipment to reduce air pollution,
  using low-sulfur coal, or removing sulfur form
  coal are too high and would increase the cost of
  electricity for consumers
• Environmentalists say
• There are cleaner ways to produce electricity
• The health and environmental costs of burning
  coal are twice its market cost
• These costs should be included in the price of
  producing electricity from coal (full-cost
  pricing) so consumers have more realistic
  knowledge about the effects of using coal to
  produce electricity

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Types and Sources of Air Pollution

• Levels of 11 common pollutants (Nitrogen Oxides,
  Asbestos, Carbon Monoxide, Tobacco Smoke -- see
  figure 17.17) are two to five times higher inside
  homes and commercial buildings than outdoors and
  as much as 100 times in some cases
• Fine particles can contain toxins and metals
  such as lead and cadmium can be as much as 60
  higher indoors than outdoors.
• Concentrations of pesticides were 10 times
  greater inside than outside
• Pollution levels inside cars can be as much as 18
  times higher than those outside the vehicles
• Top source of cancer risk a high-risk for humans

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Those At Risk

• Top source of cancer risk a high-risk for humans
• Greatest at risk
• Smokers
• Infants and children under 5
• The old
• The sick
• Pregnant women
• People with respiratory or heart problems
• Factory workers

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Sick Buildings

• New buildings are more commonly sick than older
  buildings because of reduced air exchange to save
  energy and chemicals released from new carpeting
  and furniture
• 17 of buildings are considered sick
• Costs 100 billion per year in absenteeism,
  reduced productivity, and health care costs
• Three most dangerous indoor air pollutants
• Cigarette Smoke
• Formaldehyde - from building materials,
  furniture, drapes, upholstery, adhesives in
  carpeting and wallpaper, insulation, fingernail
  hardener, winkle-free coating
• Radioactive radon-222 gas
• (Asbestos is also a problem for those working in
  factories or mines)
• (Burning of wood, dung, crop residues, and coal
  in developing countries)

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Radon Gas

• Radon-222 is a naturally occurring radioactive
  gas produced by the radioactive decay of uranium
  238. Small amounts are found in most soil and
  rocks but this isotope is much more concentrated
  in underground deposits of minerals such as
  uranium, phosphate, granite, and shale
• Can enter through cracks in foundations and
  walls, openings around pumps and drains, and
  hollow concrete blocks
• If inhaled, expose lung tissue to ionizing
  radiation can damage lung tissue and lead to
  lung cancer
• Your chances depend on
• How much radon is in your home
• How much time you spend in your home
• Whether or not you are a smoker
• The second leading cause of lung cancer after
  smoking

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Asbestos

• Asbestos - refers to several different fibrous
  forms of silicate minerals
• Was widely used in buildings and water pipes
• Unless complete sealed, it can crumble into a
  dust of fibers which can become suspended in the
  air and inhaled into the lungs
• Can cause asbestosis, lung cancer, and
  mesothelioma
• Major health risks are occurring among miners and
  workers in developing countries where it is still
  used as an inexpensive building material

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Respiratory System Mechanisms

• Mechanisms that protect from air pollution
• Hairs in the nose protect from large particles
• Sticky mucus captures smaller particles and
  dissolves some gaseous pollutants
• Sneezing and coughing expel contaminated air and
  mucus
• Cilia, mucus coated hair-like structures, line
  the upper respiratory track and transport to be
  swallowed or expelled.
• Respiratory Diseases
• Lung Cancer
• Asthma
• Chronic Bronchitis
• Emphysema

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Deaths from Air Pollution

• Estimates range from 65,000 to 200,000
• Millions more become ill and lose work time
• Worldwide - 3 million people die prematurely from
  air pollution (2.8 million are from indoor air
  pollution)

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How Are Plants Damaged By Air Pollution

• Soil nutrient depletion
• Increased susceptibility to pests, disease,
  fungi, and drought
• The greatest harm occurs to downwind coniferous
  forests at high altitudes whose needles are
  exposed to the pollution year round.
• Threatens crops reduces food production by 5 -
  10 costs anywhere from 2 - 6 billion per year

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Harmful Effects of Air Pollution on Materials

• Soot and grit on buildings, cars, and clothing
• Breaks down the exterior paint on cars and houses
  and deteriorate roofing materials
• Marble statues, historic buildings, and stained
  glass windows

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Laws Used to Reduce Air Pollution

• Clean Air Act - 1970, 1977, 1990 - the federal
  government establishes air pollution regulations
  that are enforced by each state and major cities
• National Ambient Air Quality Standards (NAAQS) -
  for six chemicals sets maximum permissible
  levels in outdoor air
• Primary standard - set to protect human health
• Secondary standard - intended to prevent
  environmental and property damage
• National Emission Standards

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How Can Air Pollution Laws Be Improved?

• Rely on prevention rather than cleanup
• Increase fuel-efficiency standards
• Regulate emissions from two-cycle gasoline
  engines
• Reduce emissions of carbon dioxide and other
  greenhouse gases

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How Is the Marketplace Used

• Emissions Trading Policy - buy and sell
• Environmentalists call this a cap-and-trade
  market approach
• Some say that it keeps a net reduction in
  pollution
• Some say that it allows the dirtier power plants
  to buy their way out and emit unacceptable
  amounts of pollutants and also to cheat

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Reducing Outdoor Pollution

• Prevention
• Burn low-sulfur coal
• Remove sulfur from coal
• Convert coal to a liquid or gaseous fuel
• Shift to less polluting fuels
• Dispersion or Cleanup
• Disperse emissions from thermal inversion layer
  with tall smokestacks
• Remove pollutants after combustion
• Tax each unit of pollution produced

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Reducing Indoor Air Pollution

• Prevention
• Cover ceiling tiles and lining of AC ducts to
  prevent release of mineral fibers
• Ban smoking or limit it to a well-ventilated
  areas
• Set stricter formaldehyde emissions standards for
  carpet, furniture, and building materials
• Prevent radon infiltration
• Use office machines in well-ventilated areas
• Use less polluting substances for harmful
  cleaning agents, paints, and other products
• Cleanup or Dilution
• Use adjustable fresh air vents for work spaces
• Increase intake of outside air
• Change air more frequently
• Circulate buildings air through rooftop
  greenhouses
• Use exhaust hood for stoves and appliances
  burning natural gas
• Install efficient chimneys for wood-burning stoves

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Individuals Matter

• PREVENT air pollution
• Reduce consumption of fossil fuels
• Reduce indoor air pollution