Air Quality Issues

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Chapter 17

• Air Quality Issues

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Humans and Air

• Food consumption is about 3 pounds per day
• Water consumption is about 2.5 liters per day (6
  pounds).
• Air consumption
• Couch potato needs about 50 pounds per day
• Someone doing light work (walking to class /
  taking notes) needs about 100 pounds per day.

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Air Pollution

• The presence in the outdoor atmosphere of one
  more contaminants or combinations thereof, in
  such quantities, and of such duration as may be,
  or may tend to be, injurious to
• Human, plant, or animal life
• Property (materials)

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Air Pollution (continued)

• or which unreasonably interferes with the
  comfortable enjoyment of
• Life, or
• Property, or
• the conduction of business

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Background of Air Pollution Problem

• London - 1952
• Conditions
• Humidity (80)
• Temperature dropping (-1C)
• Fog
• Home heating went up, which produced ash, sulfur
  oxides, and soot
• Automobiles added to the problem
• Between December 4 and 10, over 4000 people died

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Another Air Pollution Episode Donora 1948

• Donora, Pennsylvania
• In a valley
• Pollutants from zinc and steel mills became
  trapped by a temperature inversion.
• Over a period of 5 days, 17 people died.
• 5910 people became ill
• Worse for people with existing problems asthma,
  elderly, very young

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Threshold Level

• The level of pollutants below which no ill
  effects are observed
• Air pollutants have a time and concentration
  component.
• Zero threshold level (cant have any without ill
  effects)
• Dose the concentration (level) multiplied by the
  time of exposure.

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Dilution and Assimilation

• Natural processes (volcanoes, natural fires, dust
  storms) have released pollutants for millions of
  years
• Natural processes remove, assimilate, and recycle
  these pollutants.
• Humans discovered fire about 100,000 years ago.
• Simply vented combustion fumes to atmosphere.
• Dilution is the solution to pollution and if
  you dont like it MOVE

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The Atmosphere

• 78 percent nitrogen
• 21 percent oxygen
• 0.09 percent Argon
• Carbon Dioxide 0.03 percent
• Trace elements 0.07 percent
• Methane, ozone, hydrogen sulfide, carbon
  monoxide, etc...
• Water vapor can range from 0 to 4

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The Atmosphere

• As life evolved, the atmosphere has changed, but
  changes are considered natural
• For example, plants evolved to use carbon dioxide
  and releasing oxygen
• For humans, the fastest moving medium has always
  been the most convenient place to dispose of
  wastes

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Automobiles and Smog

• Engine exhausts generate brown haze
• Photochemical smog - nitrogen oxides with u.v.
  light
• N2 O2 (combustion) ? 2NO
• 2NO O2 ? 2NO2
• NO2 uv ? NO O-
• O- O2 ? O3
• O3 in presence of hydrocarbons can produce
  peroxyacetylnitrates
• Ozone can deactivate chlorophyll

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Smog

• Smog problems are worse during a (Temperature
  Inversion)
• Normal conditions - sun strikes the earth
  surface, warm air rises and mixes with air
  surface
• Inversion - cool air at the surface covered by a
  lid of warm air - no exchange occurs

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Major Pollutants and Their Effects

• The Clean Air Act of 1970/1977/1990 set Air
  Quality Standards - Levels set to protect human
  health and the environment
• Major Pollutants
• Particulates Small solid or liquid particles
  suspended in air. Smoke or haze

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Major Pollutants

• Hydrocarbons and Volatile Organic Compounds
  Gasoline, paint, solvents, cleaning solutions.
• Carbon Monoxide Carbon Monoxide - highly
  poisonous gas attaches to hemoglobin and wont
  let go.
• Nitrogen oxides - contribute to photochemical
  smog. Catalytic converters are designed to break
  this down.

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Major Pollutants

• Photochemical smog - ozone and hydrocarbons
  producing peroxyacetylnitrate.
• Sulfur oxides - Poisonous gas to both plants and
  animals
• Lead and other heavy metals
• Photochemical oxidants - Toxic to plants and
  animals. Ozone is a pollutant out of place.

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Acid problems

• Acids, mainly sulfuric and nitric
• Acid rain, acid smog, acid air, dry deposition.
  Snow accumulates then big influx of acid all at
  once.
• Combustion of fossil fuels can produce SOx and
  NOx
• Oxidizers like ozone and hydroxyl ion (OH-) can
  convert these to acids in the presence of water.

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Acid Problems (continued)

• Rain usually slightly acidic, in the range of 5.6
  to 6.0 due to some carbonic acid formation from
  CO2
• New Hampshire and Scotland pH of rain is 2.4
• Entire upper Northeastern U.S. averages 4.0 to
  4.5
• Can attack buildings, kill plants, cause problems
  in rivers and lakes

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Adverse Effects of Air Pollution on Humans,
Plants, and Animals

• Air pollution is an alphabet soup of the above
  materials
• Each pollutant varies in concentration and
  duration sources, climate, etc
• Observed effects from mixtures over a life span.
  Some pollutants work SYNERGYSTICALLY metals / pH
  example

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Effects on Human Health

• High levels of air pollution people complain of
  headaches, irritation of the eyes, nose, and
  throat, nausea, and a general ill feeling.
• Ozone - Seems to be a predominant factor in the
  irritation of mucous membranes.

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Effects on Human Health

• Acid / Particles - correlate most closely with
  asthma attacks
• Carbon Monoxide - Seem to reduce judgment,
  increase drowsiness, and increases headaches.
• Particulates - correlate with respiratory disease
  and lung cancer
• Heavy Metals Organics - carcinogens
• ALL increase stress and reduce resistance

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Determining Chronic Effects on Human Health is
Difficult!!

• Initial studies showed higher rates of lung
  disease among people living in cities with high
  air pollution
• Studies progressed, became more sophisticated
  (more difficult to interpret)
• Now the only pollution factor that clearly and
  indisputably correlates with serious lung disease
  is .CIGARETTE SMOKING

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Air Pollution and Cigarette Smoking

• Air pollution and smoking can have synergistic
  effects.
• Black Lung Disease seems to be the most prevalent
  among coal miners who were also smokers.
• Smoking reduces the activity of cilia (tiny
  hair-like cells lining lung passages).
  Particulates not removed as quickly.
• Right now, much research remains to be done

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Air Pollution - Lead

• Initially thought to enter primarily by ingesting
  leaded paint.
• Research in the early 1980s revealed that leaded
  gasoline was the primary cause
• Effects include mental retardation, learning
  disabilities, and high blood pressure.

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Effects on Agricultureand Forests

• Difficult to determine - Experimental Design??
• Plants tend to be more sensitive than humans
• Plants die from high levels of SOx and NOx
• Plants are stunted from lower levels of these
  compounds.

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Effects on Agricultureand Forests

• Estimates of growth WITHOUT the current ozone
  pollution problem
• Plant Increase
• Corn 3
• Wheat 8
• Soybeans 17
• Peanuts 30
• Estimated 5 billion dollar increase in
  agricultural production

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Effects on Materialsand Aesthetics

• Particulates turn things gray.
• Paint and fabric deteriorate more quickly
• Rubber becomes hard and brittle
• Metals and stonework may be corroded
• Visibility reduced (aesthetics)

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Primary Air Pollutants

• Pollutants Products of Combustion
• Complete Combustion
• CH4 2O2 ? CO2 2H2O this rarely happens
• Direct Pollutant Products
• Carbon ? particulates
• CH4 ? hydrocarbons
• if not enough O2 ? carbon monoxide
• Nitrogen from air ? NOx
• Fuel impurities Sulfur ? SOx

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Secondary (Indirect) Products

• Photochemical Smog
• If hydrocarbons were not present, nitrogen and
  oxygen form NOx and there would be no
  accumulation of O3
• Additionally excess N forms peroxyacetyl nitrates
  (PAN)
• Xenobiotic compound
• Acids form from SOx and NOx
• Sulfuric Acid, Nitric Acid

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The Greenhouse Effect

• Caused by the heat trapping effects of Carbon
  Dioxide
• Similar to automobile interiors heating up
• Visible light passes through windshield
• Strikes the surface of interior objects
• Surfaces heat up and emit thermal infrared
  electromagnetic energy
• Thermal infrared cannot pass through the glass,
  so interior heats up

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The Spaceship Earth

• Temperatures we are accustomed to are caused by a
  carbon dioxide concentration of approximately
  (0.03) or 300 ppm.
• 300 ppm levels caused by the photosynthesis /
  respiration cycle
• During the last century, fossil fuels combustion
  has changed the picture
• For every one pound of fuel burned, nearly 3
  pounds of CO2 are formed

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CO2 Issues

• Each year approximately 2 billion tons of fossil
  fuel are burned
• 5.5 billion tons of CO2
• 1.7 billion tons of CO2 due to the clearing and
  burning of tropical forests
• The result
• in 1900 CO2 levels averaged 290 ppm
• in 1989 CO2 levels averaged 350 ppm
• in 1998 CO2 levels averaged 362 ppm

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Probable Effects

• Average world wide temperature will increase by 3
  to 18C.
• Changes at polar regions will likely be greater
  than changes at equator
• What will temps be like 10 to 15 warmer
• Polar Ice Melting
• Rainfall patterns may change
• Agricultural patterns will change

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Is the Greenhouse Effect Here?

• We know the effects of CO2
• We know that CO2 has increased
• We also know that the earth has experienced
  natural fluctuations in temperature
• We have accurate climate records for about 100
  years
• The 1980s set a new record for high temps
• The 1990s set a new record again

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Depletion of the Ozone Shield

• Ultraviolet electromagnetic energy from the sun
• Absorbed by biological tissues - destroys
  proteins and DNA
• Less than 1 of UV that strikes the upper
  atmosphere of the earth reaches the surface of
  the planet
• Causes sunburns
• 200,000 - 600,000 cases of skin cancer per year

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How does O3 get to the Stratosphere?!!

• UV strikes O2 molecule
• O2 splits into two separate (free) O-atoms.
• Three of the O- atoms come together to form O3
• Absorbs 99 percent of the suns UV radiation.

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So what is the problem??

• Chloride (Cl-) combines more easily with free O-
  than other O- atoms.
• Chlorofluorocarbons (Cl-F-C) find their way to
  the stratosphere.
• UV breaks down CFCs and releases free Cl-
• The Cl- combines with free O- and prevents the
  formation of O3

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CFCs and Ozone

• Cl- O3 ? ClO O2
• ClO O- ? Cl- O2
• The chlorine acts as a catalyst a single
  chlorine atom can act for up to 65 years!!!

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Where do CFCs come from??

• Used in all refrigeration, air conditioners, and
  heat pump units.
• Used in making plastic foams - like styrofoam.
• Used to clean computer chips.

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Ozone Hole

• Discovered over the South Pole in 1985.
• In 1989, another hole was discovered over the
  North Pole.
• UV radiation is deadly to phytoplankton
• In 1986 the Montreal Accord was signed 50
  reduction in CFC by 1999.
• 1989 Helsinki Accord - Phase out all CFCs by
  2000.
• U.S. stopped manufacturing CFCs in 1996