Air Pollution

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• Air Pollution Sources Effects
• Most local air pollution associated with cities,
  esp. large cities and industrial centers
• Average concentration of airborne particles in
  urban areas 10x concentration in rural areas
• Major cities air pollution causes thousands of
  deaths each year
• Los Angeles 6000
• New York 4000
• Detroit 2000
• Mexico City Air quality so severe that some
  people estimate breathing is equivalent to
  smoking two packs of cigarettes a day
• Many air pollutants are hygroscopic
• Combine with water and promote fog formation
• Particulate matter can affect local precipitation
• Boulder, CO Power plant produced fly ash
  aerosols and induced snowfall

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• Air Pollution Components
• Primary
• Problematic in the form in which theyre produced
• Ex Lead, carbon monoxide
• Secondary
• Require modification
• Ex Ozone
• Many are components of photochemical smog
  (react chemically with light)
• Legislation addressing air pollution requires
  consideration of both primary and secondary
  pollutants
• Clean Air Act 1970
• Clean Air Act Amendments 1990
• EPA NAAQS for six criteria pollutants

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• Air Pollution Components
• Particulate Matter
• Sources
• Combustion of fossil fuels, especially coal
• Mobile sources Cars, trucks
• Stationary sources Power plants, industrial
  furnaces, wood stoves
• Effects
• By the 1950s, air quality in London had
  deteriorated so much that incidences of death due
  to pollution werent uncommon
• 1952 Killer Smog in London ? 4000 deaths
• Health Respiratory impairment, lung damage,
  lung cancer
• Especially children, elderly, people with chronic
  respiratory problems
• Acidic PM can damage structures, reduce
  visibility

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LA - 1943
NYC - 1963
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• Air Pollution Components
• Particulate Matter
• Trends
• EPA Standards
• Pre-1987 TSP (Total Suspended Particulates)
• Post-1987 PM10 (Particles lt 10 µm)
• Post-1997 PM2.5 (Particles lt 2.5 µm)
• NAAQS for PM10
• Annual average 50 µg m-3 (revoked Dec 2006)
• Daily peak 150 µg m-3
• NAAQS for PM2.5
• Annual average 15 µg m-3
• Daily peak 35 µg m-3

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1990-2009 Direct PM10 emissions down 67
http//www.epa.gov/air/airtrends
1990-2009 Direct PM2.5 emissions down 50
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• Air Pollution Components
• Carbon Monoxide
• Colorless, odorless gas
• Produced by incomplete combustion of fossil fuels
  (too little O2 supplied in a normally tuned
  engine)
• Sources
• About 56 of CO emissions nationwide from on-road
  motor vehicles (24 from non-road vehicles)
• In cities, 85-95 of CO from motor vehicles
• Diesel engines typically produce less CO but more
  PM than gasoline engines
• Alternative to complete combustion of fuel is
  combustion of exhaust
• Produces hazardous amounts of heat
• Combustion temperature can be lowered using
  catalyst
• Chemical catalysts poisoned by lead

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• Air Pollution Components
• Carbon Monoxide
• Effects
• CO binds to hemoglobin in place of oxygen
• Affinity for CO 200x higher than for O2
• Continued exposure can lead to
• Impairment of vision
• Difficulty estimating time
• Reduced manual dexterity
• Poor learning ability
• Difficulty performing complex tasks
• Greater risk of heart attacks in people with
  certain forms of heart disease (e.g. angina)
• Contributes to formation of ground-level ozone

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1990-2008 Vehicle miles traveled increased 36
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• Air Pollution Components
• Nitrogen Oxides (NOx)
• Principally NO2
• Highly reactive reddish-brown gas
• Play a major role in the formation of ozone, PM,
  haze and acid rain
• Important component of photochemical smog
• Sources
• Forms from FF combustion at high temperatures
• Mobile Cars trucks (58)
• Stationary Power plants (34), home heaters,
  gas stoves, industrial plants (8 total)
• Formation could be controlled by using pure
  oxygen for combustion (impractical and dangerous)
• Formation reduced by low-temperature combustion

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Denver
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• Air Pollution Components
• Nitrogen Oxides (NOx)
• Effects
• Strong oxidizing agent
• Reacts readily in air to form nitric acid and
  nitrates
• Health
• Irritates lungs and lower resistance to
  respiratory infections
• Lung damage
• Environment
• Damages plant foliage, impairs growth
• Precursor of ground-level ozone, PM, smog
• Contributes to acid rain
• - Leaching of minerals from soil
• - Acidification of lakes and waterways
• Contributes to eutrophication of lakes
  waterways
• Contributes to global warming (N2O)

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