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Climate Change and Ozone Depletion
How might the earth’s temperature and climate change in the future?
A. Temperature and climate have been changing throughout the earth’s history.
1. Climate shifts have occurred due to volcanic emissions changes in solar input, continents moving
on shifting plates, meteor strikes and other factors.
2. Alternating cycles of freezing and thawing are known as glacial and interglacial periods.
B. Geologic records and atmospheric measurements provide a wealth of information about past
atmospheric temperatures and climate.
1. Antarctic ice cores contain tiny gas bubbles. Analysis of the radioactive isotopes in the trapped gas
gives us information about historical atmospheric composition, greenhouse gas levels, and
temperature.
2. Sediment cores are also analyzed for pollen, fossils and other clues about ancient plant types.
3. Direct temperature records go back to 1861.
C. A natural process called the greenhouse effect warms the lower troposphere and surface.
1. Light energy from the Sun enters our Earth’s atmosphere. Some of the energy is reflected back
into space and some of it is absorbed. Different features of the surface of our planet reflect or
absorb the energy differently.
2. The absorbed light energy is converted into heat energy. A layer of greenhouse gases in the
atmosphere prevents the heat from escaping.
3. As a result of the greenhouse effect, the Earth’s surface temperature is much warmer than it
would be without it.
D. The four major greenhouse gases in the lower atmosphere are water vapor, carbon dioxide, methane,
and nitrous oxide.
1. Water Vapor (H2O) – most abundant greenhouse gas; positive feedback loop = warmer air holds
more moisture, moisture makes air warmer
2. Carbon Dioxide (CO2) – enters the atmosphere through the burning of fossil fuels, solid waste,
trees and wood products, etc. It is removed from the atmosphere or “sequestered” when it is
absorbed by plants as part of the carbon cycle.
3. Methane (CH4) – emitted during the production and transport of fossil fuels, from livestock and
other agricultural practices, and by the decay of organic waste in municipal solid waste landfills.
4. Nitrous Oxide (N2O) – emitted during agricultural and industrial activities and during
combustion of fossil fuels and solid waste.
E. Humans have increased levels of greenhouse gases in the troposphere by use of fossil fuels, farming,
use of inorganic fertilizers, burning forests, etc.
1. Burning of fossil fuels has generated much of the CO2 increase.
2. Deforestation and clearing grasslands release CO2 and N2O.
3. Increased cattle raising and other livestock has added methane release.
4. Use of inorganic fertilizers in rice cultivation releases N2O into the troposphere.
F. The countries with the highest emissions of CO2:
1. The United States (30%)
2. China (5%)
3. The European Union
G. The Intergovernmental Panel on Climate Change (IPCC) was formed to evaluate possible climate
changes. Many of the findings of the IPCC support the scientific consensus that the troposphere is very
likely (90-99% probability) getting warmer. There is evidence that the earth’s troposphere is warming,
mostly because of human actions.
1. The 20th century was the hottest century in the past 1,000 years
2. Since 1861 the average global temperature has risen 0.74 degrees centigrade, with most increase
occurring since 1980.
3. The 10 warmest years since 1861 have occurred since 1990.
4. Arctic temperatures have risen almost twice as fast as those in the rest of the world.
5. Glaciers and ice sheet in some parts of the world are melting and shrinking at increasing rates.
6. Warmer temperatures in Alaska and Russia are melting the permafrost, releasing more
greenhouse gases into the troposphere.
7. The world’s average sea level rose by 10-20 centimeters (4-8 inches).
8. The range and distribution of plan and animals is shifting towards the poles.
9. In the mid-latitudes, spring is coming earlier and winter is coming later.
H. A number of natural and human-influenced factors might amplify (positive feedback) or dampen
(negative feedback) projected changes in the average temperature of the troposphere.
I. Can increased solar activity be the cause of recent temperature increases? No. Since 1975, the
troposphere has warmed while the stratosphere has cooled. A hotter sun would cause the entire
atmosphere to warm.
J. The oceans can absorb large amounts of CO2 (25-30% of man-made CO2 is absorbed by the ocean).
But, there are problems associated with this absorption:
1. The warmer water gets, the less soluble it is to gases like CO2, so as global warming increases,
this phenomenon will decrease.
2. The addition of CO2 increases the acidity of the ocean (carbonic acid) which harms marine life,
especially coral reefs.
K. One of the largest unknowns in global warming is the change in distribution of clouds.
1. Additional clouds may have a warming effect by absorbing and releasing more heat into the
troposphere, or a cooling effect by reflecting more sunlight back into space.
2. Several factors will affect the net result of more cloud cover such as the amount of water vapor in
the troposphere, whether clouds are thin or thick, coverage, altitude of the cloud, size and number
of water droplets or ice crystals formed in clouds.
L. Aerosol or particulate pollutants and soot can warm or cool the troposphere.
1. Global dimming refers to the idea that particulates in the atmosphere can slightly shade that
Earth and reduce the amount of solar energy reaching the Earth’s surface.
2. Scientists hypothesize that pollution can dim sunlight in two ways: soot particles in the
atmosphere reflect some of the sunlight back into space; airborne particles cause more water
droplets to condense out of the air, leading to thicker, darker clouds.
3. This phenomena will decrease as particulate pollution standards are enforced.
M. Computer models are used to project future changes in the earth’s average temperature. These models
are adapted as we discover new inputs and outputs for heat and greenhouse gases in our complicated
earth system. Current computer models are the most sophisticated yet.
CORE CASE STUDY: NASA scientists used the 1991 eruption of Mount Pinatubo in the
Philippines to test the predictive power of their climate model. They predicted that the SO2 and
particulates would cool the planet by 0.5º C and that everything would be back to normal by 1995.
As it turns out, the prediction was extremely accurate and the validation led to more trust and
confidence in the predictions that computer climate models are able to make.
What are some possible effects of a warmer atmosphere?
A. A rapid increase in the temperature of the troposphere during this century would give us little time to
deal with its harmful effects.
1. Local weather (weather in your area) may not change as obviously as global climate (average
temp. and precip. for the planet as a whole).
2. Many scientists fear a “tipping point” after which severe climate changes cannot be prevented.
3. Global warming refers to temperature increases in the troposphere, which can cause climate
change.
4. Global climate change is a broader term that refers to changes in any aspects of the earth’s
climate.
B. Severe drought accelerates global warming and can lead to more droughts.
1. A severe lack of water, growth of trees and other plants will slow, less CO2 taken out of
atmosphere, in addition, more forest and grass fires will add CO2 the atmosphere
2. Groundwater, lakes, and rivers will be depleted because of lake of precip., increased evaporation,
and increased need to agricultural irrigation.
C. The melting of some of the world’s ice means that less sunlight is reflected back into space, and
helps warm the troposphere further.
1. Increasing temperature tends to be greater in the polar regions. Scientists consider these areas as
early warning sentinels of changes in average temperature of earth’s troposphere.
2. Floating ice is melting faster than it is being formed. Ice formations are important for helping to
cool the earth by reflecting 80-90% of incoming light back into space. Once the ice is melted, the
water it is replaced by absorbs 80-90% of incoming light.
3. It is estimated that up to half of the Arctic sea ice could disappear by 2050. This would shift the
storm-guiding jet stream northward and result in great climate change for North America and Europe.
4. Loss of frozen water means a loss of reservoirs of water for warmer months of the year. Many
global populations rely on this melt water for drinking.
D. Global sea levels are very likely to rise during this century. The projected rise in sea level is about 18–59
cm (0.6–1.9 feet), but higher amounts are possible.
1. 2/3 of this rise is the result of thermal expansion of warm water. The other 1/3 of the rise will be
from the melting of land-based ice shelves.
2. Harmful effects of this rise in sea level include:
a. threatening half the world’s estuaries and wetlands and coral reefs
b. disruption of many of the world’s coastal fisheries
c. flooding of low-lying islands and gently sloping coastlines will erode and retreat inland
d. flooding of agricultural lowlands and deltas where much of the world’s rice is grown
e. contamination of freshwater coastal aquifers with salt water
f. submergence of some low-lying islands in the Pacific Ocean and Indian Ocean
E. Another dangerous scenario is the melting of the arctic permafrost. As arctic temperature increases,
permafrost melts and the organic matter in soils and lake bottoms decomposes, releasing CH4, a
greenhouse gas.
F. Global warming could alter ocean currents and cause excessive warming in some parts of the world
and severe cooling in others.
1. Oceans help moderate the earth’s average surface temperature by absorbing both CO2 and heat
from the atmosphere.
2. Ocean currents are also important for storage of CO2 and transfer of heat.
3. Movement and speed of the ocean currents may contribute to significant alterations in
temperature patterns in the northern hemisphere.
4. Changes in the hydrologic cycle may affect global precipitation patterns. It may result in regional
warming or cooling because of changes in the movement of ocean currents and air masses.
G. Global warming will lead to changes in precipitation and weather extremes.
1. Certain areas will be prone to prolonged heat waves and droughts while other areas will
experience prolonged heavy rains and increased flooding.
2. Hurricanes will also get stronger because of an increase in ocean water surface temperatures.
This warm water is the source of a storms power.
H. A warmer troposphere will cause changes in biodiversity by altering the distribution and population
sizes of wild species, shift locations of ecosystems and threaten some protected reserves and coral
reefs.
1. A warmer climate could expand the ranges and populations of plant and animal species that can
adapt to warmer climates.
2. Warming could also threaten plants and animal species that can’t migrate rapidly enough to new
areas.
3. Ecosystems most likely to be disrupted are coral reefs, polar seas, coastal wetlands, arctic and
alpine tundra and high-elevation mountaintops.
I. Climate change will shift the areas where crops are grown. Food production may increase in some
areas and decrease in others.
1. Warmer temperatures could shift growing areas farther north, but les fertile soils in these areas
may reduce food production.
2. Lower productivity could be offset by longer growing seasons.
3. Genetically engineered crops can be developed to withstand the temp./ precip. extremes.
J. Global warming will threaten human health by increasing deaths from heat stroke, malnutrition and
starvation from the disruption of food supplies, increased flooding, the spread of tropical diseases to
temperate areas, more insects, microbes, toxic molds, and fungi, an increase in some forms of air
pollution, more O3, greatly increased number of environmental refugees from drought and flooding, and
poverty.
What can we do to slow climate change?
A. Climate change is hard to deal with because it has many causes, its effects are uneven and long-term,
and there is disagreement over what should be done.
1. The problem is global.
2. The pollutants are all but invisible and the problem is only apparent as gradual changes over a
long period of time
3. The effects will last a long time.
4. The harmful and beneficial impacts of climate change are not spread evenly.
5. Many actions that might reduce the threat of climate change, such as phasing out fossil fuels, are
controversial because they can disrupt economics and lifestyle.
B. There is disagreement over what we should do about the threat of global warming.
1. Scientists, economists, business leaders, and political leaders debate the causes, how rapidly the
changes might occur, the effects on humans and ecosystems and the responses that should be
taken.
2. Mitigation is the act of decreasing or reducing something. This is when we take actions aimed at
reducing the extent of global warming by reducing the production of greenhouse gases or their
emission into the atmosphere
3. Adaptation means that we recognize some warming is unavoidable and devise strategies to
reduce its harmful effects, or live with the outcome.
C. The solutions offered for slowing the rate and degree of global warming come down to three major
strategies: improve energy efficiency to reduce fossil fuel use, shift from carbon-based fossil fuels to
a mix of carbon-free renewable energy resources, and sequester or store as much CO2 as possible in
soil, in vegetation, underground, and in the deep ocean.
D. We can remove and store some CO2 we produce as shown in figure 19-15.
1. Plant trees that will store CO2 in biomass.
2. Soil sequestration is a possibility, but warmer temperatures can increase soil decomposition with
CO2 then being returned to the troposphere.
3. Reduce release of CO2 and nitrous oxide from soil by altering agriculture practices to include notill cultivation and letting fields lie fallow.
4. Remove CO2 from smokestacks and pump it deep underground or inject it into the deep ocean.
There are several problems with this approach at present.
E. Governments can tax emissions and energy use, increase subsidies and tax breaks for saving energy
and using renewable energy, and decrease subsidies and tax breaks for fossil fuels.
1. One possible solution is to phase in carbon taxes on fossil fuel use and at the same time decrease
taxes on income, labor, and profits to offset the consumption taxes.
2. Greatly increase government subsidies for energy-efficiency and carbon-free renewable-energy
sources.
F. It will probably cost less to help slow global warming now than to deal with its harmful effects later.
1. Some studies indicate that implementing conservation strategies would boost the global and U.S.
economies instead of hurt it.
G. The Kyoto Protocol, developed in 1997 would require 38 developed countries to cut emissions of
some gases by about 5.2% below 1990 levels by 2012.
1. Developing countries would not have to make cuts until a later date.
2. By mid-2004 it had been ratified by more than 120 countries.
3. In 2001, President George W. Bush withdrew the U.S. from the Kyoto Protocol.
a. Argued that it would harm the U.S. economy
b. Objected to the fact that China, India, Brazil, Indonesia and other rapidly developing countries
were exempt from the first phase of the protocol.
H. Many countries, states, cities, companies, schools, and individuals are reducing their greenhouse gas
emissions, improving energy efficiency, and increasing their use of carbon-free renewable energy.
1. The ultimate goal of many is to become carbon neutral – a balance between the amount of
carbon released into the atmosphere and the amount sequestered or removed from the
atmosphere.
I. Many countries and cities are looking for ways to cope with the harmful effects of climate change.
1. Estimates are that current emissions of greenhouse gases must be cut by at least 60% by 2050 to
stabilize concentrations at their present levels.
2. For political and economic reasons, such a reduction is extremely unlikely.
3. We should begin to prepare for possible effects of long-term atmospheric warming.
How have we depleted ozone in the stratosphere and what can we do about it?
A. The ozone layer that is concentrated in the stratosphere absorbs about 95% of harmful UV radiation.
Less ozone in the stratosphere will allow more harmful UV radiation to reach earth’s surface. The
overwhelming consensus of researchers is that ozone depletion is a serious threat to humans, other
animals, and some of the primary producers that support earth’s food.
B. Widespread use of a number of useful and long-lived chemicals has reduced ozone levels in the
stratosphere.
1. Chlorofluorocarbons (CFC) were used coolants in air conditioners and refrigerators, propellants
in aerosol cans, etc. Freon was the most widely used of these.
2. They had many uses and became very popular since they were inexpensive to manufacture and
seemed to be dream chemicals.
3. In 1974, chemists Rowland and Molina found that CFCs were lowering the average concentration
of ozone in the stratosphere. Four major conclusions came from their research:
a. CFCs remain in the atmosphere because they are insoluble in water and chemically unreactive.
b. While in the troposphere, CFCs act as greenhouse gases. Over 11-20 years these chemicals
are lifted into the stratosphere, mostly by convection currents and turbulent mixing of air.
c. CFC molecules break down under the influence of high-energy UV radiation. Chlorine is
released and is highly reactive. Fluorine, bromine and iodine are also released. This causes
ozone to be broken down faster than it is formed.
d. These CFC molecules can last in the stratosphere for 65-385 years.
4. In 1988, after 14 years of delay tactics, the CFC industry acknowledged that CFCs were depleting
the ozone and agreed to stop manufacture of them.
C. During four months of each year up to half of the ozone in the stratosphere over Antarctica and a
smaller amount over the Arctic is depleted.
1. Ozone loss is often called the ozone hole, but it is actually ozone thinning.
2. The total area of stratosphere that suffers from ozone thinning varies from year to year.
3. The primary culprits are CFCs and other ODCs.
4. The polar vortex is a swirling mass of very cold air that is isolated from the rest of the atmosphere
for several months. Ice crystals in this mass collect CFCs and other chemicals and set up
conditions for formation of CIO, the molecule most responsible for seasonal loss of ozone.
5. As sunlight returns to Antarctica in October, the light stimulates CIO molecules and within a
matter of weeks the ozone is reduced by 40-50% on average.
D. Increased UV radiation reaching the earth’s surface from ozone depletion in the stratosphere is
harmful to human health, crops, forests, animals, and materials such as paints and plastics. Figure
20-21 lists the effects of ozone depletion.
E. Exposure to UV radiation is a major cause of skin cancers.
1. The primary cause of squamous cell and basal cell skin cancers is years of exposure to UV-B
radiation. Fortunately, 90-95% of these cancers can be cured if detected early enough.
2. Malignant melanoma is a third type of skin cancer that may occur anywhere on the body. It kills
a fourth of its victims (most under the age of 40) within 5 years.
3. Women who used go tanning at least once a month increase chances of developing melanoma by
55%.
4. Caucasians are most susceptible to melanomas.
F. To reduce ozone depletion we must stop producing all ozone-depleting chemicals.
1. If we immediately stop producing all ozone-depleting chemicals it will take 60 years for the
ozone layer to return to 1980 levels and about 100 years to return to pre-1950 levels.
2. The Montreal Protocol is an international treaty that controls the production and consumption of
chemical that destroy the ozone layer. Its goal was to cut emissions of CFCs by about 35%
between 1989 and 2000. It has been quite successful in eliminated CFC production and use.
3. Representatives met again in 1990 and 1992 and adopted the Copenhagen Protocol, an
amendment that strengthened and accelerated the phase out of key ozone-depleting chemicals.
4. These agreements have now been signed by 191 countries
Air Pollution
What is the nature of the atmosphere?
A. The atmosphere consists of several layers with different temperatures, pressures, and composition
1. The atmosphere is a thin layer of gases divided into several spherical layers.
2. Density and atmospheric pressure vary throughout the atmosphere due to gravitational forces that
pull the gas molecules toward the earth’s surface. Air at sea level has a higher density than air at
the top of a mountain.
3. Atmospheric pressure is a measure of the mass per unit of air. It decreases with altitude.
B. About 75-80% of the earth’s air mass is found in the troposphere, the atmospheric layer closest to the
earth'’ surface.
1. About 99% of the volume of air is made up of nitrogen (78%) and oxygen (21%) with the rest
consisting of water vapor, argon, carbon dioxide and traces of several other gases.
2. This layer is also responsible for short-term weather and long-term climate.
C. The stratosphere is the second layer of the atmosphere and extends from 11-30 miles above the
Earth’s surface.
1. The concentration of ozone in this layer is much higher than in the troposphere.
2. This “global sunscreen” keeps about 95% of the sun’s harmful UV radiation from reaching the
earth’s surface and protects us from sunburn, cataracts, cancer of skin and eye and damage to our
immune system.
3. There is evidence of a decrease in “good” ozone in the stratosphere and increase in “bad” ozone in
the troposphere.
What are the major outdoor air pollution problems?
A. Air pollution is the presence of chemicals in the air in concentrations high enough to cause harm.
1. Natural sources of air pollution such as dust particles, organic chemicals released by plant decay;
forest fires, etc. rarely reach harmful levels.
2. Human sources are burning fossil fuels in vehicles and power and industrial plants. Increased use
of fossil fuels has greatly increased the amount of air pollution, especially in urban areas where
people, cars and industry are concentrated.
3. Cities generally have higher pollution levels than rural areas. Winds can carry these pollutants
away from their source to other areas.
B. Primary pollutants are pollutants emitted into the air. Secondary pollutants are when primary
pollutants react with one another and/or with air to form new chemicals.
C. Major air pollutants include carbon oxides, nitrogen oxides, sulfur oxides, particulates, ozone, volatile
organic compounds, and radon.
1. Carbon oxides – Carbon monoxide is the result of incomplete combustion of fossil fuels.
Carbon dioxide is the main component of the carbon cycle. 93% of carbon dioxide is natural,
the other 7% is released into the atmosphere by human activities like burning fossil fuels.
2. Nitrogen oxides – Nitrogen dioxide is produced when nitrogen and oxygen react during high
temperature reactions inside car engines or coal-burning power plants. Nitrogen dioxide can
combine with water vapor in the air to make nitric acid which contributes to acid rain.
3. Sulfur oxides – Sulfur dioxide is a part of the sulfur cycle and is also formed through the
burning of coal containing sulfur. Sulfur dioxide can combine with water vapor in the air to make
sulfuric acid which contributes to acid rain.
4. Particulates – are tiny particles that are light enough to be suspended in air. They can have
natural sources like forest fires, volcanoes, and dust storms. Many more result from human
activities like the combustion of various materials like wood, coal, or oil.
5. Ozone – a high reactive and unstable form of oxygen. “Good” ozone in the stratosphere protects
us from harmful UV radiation. “Bad” ozone in the troposphere is a main component of
photochemical smog.
D.
E.
F.
G.
H.
6. Volatile organic compounds – are organic compounds that have high enough vapor pressures to
vaporize at room temperature and enter the atmosphere. They are widely used in household
chemicals including cleaners, paints, solvents, and fuels.
Industrial smog is a mixture of sulfur dioxide, droplets of sulfuric acid, and a variety of suspended
solid particles emitted by burning coal and oil.
1. When coal is burned it is converted to carbon dioxide and carbon monoxide and unburned carbon
particles (soot).
2. Coal and oil also contain sulfur (in the form of iron sulfide) that is then converted to sulfur dioxide.
3. Reactions with water vapor changes sulfur dioxide to sulfuric acid in several steps. These
droplets can then react with ammonia in the atmosphere to form ammonium sulfate. These
various components give the air a gray color.
4. Most countries have adopted pollution controls, but several countries with industrialized urban
areas have serious smog problems.
CORE CASE STUDY: South Asia’s Massive Brown Cloud. Much of Southeastern Asia has a huge
brown cloud of industrial smog from coal burning. The rapid industrialization of China and India is
paralleling the industrial revolution during the 19th and early 20th century in Europe and the U.S.. Solar
energy reaching the earth is reduced 2-15% in some areas. Crops, trees and life in lakes are being
damaged along with a higher number of premature deaths from respiratory diseases. This huge brown
cloud also seems to be causing changes in regional climate, warming some areas and cooling others.
Photochemical smog is formed by the reaction of nitrogen oxides and volatile hydrocarbons under
the influence of sunlight.
1. A photochemical reaction is any chemical reaction activated by light.
2. Nitrogen dioxide found in photochemical smog is a yellow-brown gas with a noxious odor and
causes a brownish haze to form.
3. Some NO2 reacts with hydrocarbons to produce a mixture of ozone, nitric acid, aldehydes, and
other pollutants.
4. These substances are oxidizing agents and can irritate the respiratory tract, damage crops and trees.
5. Photochemical smog is more common in cities in warm, dry, sunny areas.
Outdoor air pollution can be reduced by precipitation, sea spray, and winds and increased by urban
buildings, mountains, and high temperatures.
1. Some factors help reduce outdoor air pollution: heavy particles settle out of atmosphere due to
gravity; rain and snow; salty sea spray; winds; and chemical reactions of pollutants. Each of
these factors helps remove pollutants, but they are then deposited elsewhere.
2. Some factors can increase outdoor air pollution: urban buildings; hills and mountains; higher
temperatures; VOC emissions from certain trees and plants; the grasshopper effect where volatile
compounds are carried from tropical or temperate areas to the poles; and temperature inversions.
Temperature inversions occur when a layer of warm air sitting on top of a layer of cool air near the
ground can prevent outdoor pollutants from rising and dispersing.
1. Normally, turbulence, caused by the mixing of warm and cold air disperses air pollutants.
2. A temperature inversion prevents the mixing of air and it becomes stagnant and accumulates
more pollutants.
3. Two areas are particularly susceptible to inversions:
a. a city located in a valley surrounded by mountains that experiences cloudy, cold weather.
b. a sunny climate, light winds, mountains on three sides and several million people and vehicles
(Los Angeles basin).
Cities and urban areas are often called heat islands because they can sometimes be 2-10° warmer
than the surrounding countryside.
1. This is caused by the buildings and pavement replacing the trees and vegetation.
2. The increased temperature can lead to more air pollution by causing thermal inversions or smog
which requires heat to form.
What is acid deposition and why is it a problem?
A. Sulfur dioxide, nitrogen oxides, and particulates react with water vapor in the atmosphere to produce
various acidic chemicals that travel long distances before coming back to earth.
1. Acidic particles remain in the atmosphere for 2-14 days, depending on the prevailing winds,
precipitation, and other weather patterns.
2. The acidic substances return to earth in one of two forms:
a. wet deposition as acidic rain, snow, fog, and could vapor with a pH less than 5.6.
b. dry deposition as acidic particles
3. Acid deposition is a problem in areas downwind from coal-burning facilities and urban areas.
4. Many acid-producing chemicals generated in one country end up in other countries due to
prevailing winds.
B. Acid deposition causes harm in a number of ways:
1. It can cause or worsen respiratory disease through the inhalation of acidic particles.
2. Acid precipitation negatively affects aquatic ecosystems. Many lakes in northern Europe and the
eastern U.S. have few, if any, fish due to decreased pH.
3. Effect of acid deposition on plants is caused partly by chemical interaction in the soils. Acid
deposition can deplete some soil nutrients
4. Acid rains can release toxic ions into soil. It can also dissolve aluminum, cadmium, and mercury ions
from the soil. These ions are toxic to plants and animals. Some can make their way into human
drinking water sources.
5. Weaken plants that become susceptible to other stresses because weakened trees are more
susceptible to diseases. The mountaintop trees are those that are most harmed by acidic rain
because they are also growing in thin soils.
6. Acid can attack metallic and stone objects. Large amount of money are spent each year to clean
and repair monuments and statues damages by acid deposition.
C. Progress has been made in reducing acid deposition in the U.S., but there is a long way to go.
1. The 1990 amendments to the Clean Air Act have lead to significant reductions in SO2 and NOx
emissions from coal-fired power and industrial plants.
2. It is predicted that an additional 80% reduction in SO2 emissions would be needed to allow
northeastern streams and lakes to recover from the effects of acid deposition.
D. A number of prevention and control methods can reduce acid deposition, but they are politically
difficult to implement.
1. The best approaches are those that reduce or eliminate emissions of SO2, NOx and particulates.
2. Use of low sulfur coal is both good and bad, it lowers the amount of SO2 released but because
more must be burned to generate the same amount of electricity, it emits more mercury, CO2, and
radioactive particles.
3. Approaches to neutralize acid lakes include adding limestone or lime to the water or soil or
adding a small amount of phosphate fertilizer, this approach is being evaluated.
What are the major indoor air pollution problems?
A. Indoor air pollution is usually a much greater threat to human health than outdoor air pollution.
1. EPA studies have shown that:
a. Levels of 11 common pollutants are 2-5 times greater inside homes and commercial buildings
than outside.
b. Health risks are magnified because people usually spend 90% of their time indoors or in vehicles.
2. Living organisms’ excrement, from organisms like dust mites and cockroaches, play a role in the
almost threefold increase in asthma cases between 1972 and 2002.
3. Toxic airborne spores of molds and mildew that grow under houses and on inside walls can cause
headaches, allergic reactions, and aggravate asthma and other respiratory diseases.
4. Sick-building syndrome is the name given to the health effects people experience that appear to
be related to time spent in a particular building. The symptoms disappear soon after leaving the
building. SBS has been linked to various air pollutants such as VOCs and biological pollutants,
and new buildings are apt to be more prone to this than old buildings due to poor air ventilation.
5. The EPA lists the four most dangerous indoor air pollutants in developed countries as cigarette
smoke, formaldehyde, radioactive radon-222 gas, and very small fine and ultrafine particles.
B. Formaldehyde is the chemical that causes most people in developed countries difficulty. It is used to
manufacture common household materials.
CASE STUDY: Radon-222 gas is a colorless, odorless, naturally occurring radioactive gas created by the
decay of radium found in some soils and rocks, and can seep into some homes and increase the risk of
lung cancer. Radon gas tends to be pulled into homes because of the slightly lower atmospheric pressure
inside most homes. Radon is thought to be the second leading cause of lung cancer deaths each year in
the U.S. Remedies include sealing cracks in foundation and walls, increase ventilation and use a fan for
cross ventilation.
What are the health effects of air pollution?
A. The respiratory system has several ways to help protect you from air pollution.
1. Hairs in the nose filter out large particles. Sticky mucus lines the respiratory trap to capture
smaller particles and some dissolved gases.
2. Sneezing and coughing expel contaminated air and mucus.
3. Prolonged or acute expose to air pollutants can overload or break down the natural defenses.
4. Several respiratory diseases can develop such as asthma, lung cancer, chronic bronchitis and
emphysema.
5. People with respiratory diseases, older adults, infants, pregnant women, and people with heart
disease are especially vulnerable to air pollution
B. Each year, air pollution kills about 3 million people, mostly from indoor air pollution in developing
countries. Air pollution deaths in the U.S. range from 150,000 to 350,000 people per year.
How should we deal with air pollution?
A. The U.S. Congress passed Clean Air Acts in 1970, 1977, and 1990. This also led to the creation of
the Environmental Protection Agency (EPA) to enforce this policy.
1. National Ambient Air Quality Standards (NAAQS) were established and enforced for six outdoor
criteria pollutants: nitrogen oxides, ozone, sulfur dioxide, carbon monoxide, lead, and particulates.
(Remember: NOSCLP)
2. Two limits were established: a primary standard is set to protect human health and a secondary
standard is set to prevent environmental and property damage.
3. EPA has established national emission standards for 188 hazardous air pollutants (HAPs) that
may cause serious health and ecological effects. These include neurotoxins, carcinogens,
mutagens, teratogens, and others.
4. Great news: According to a 2005 EPA report, combined emissions of the six criteria air
pollutants decreased by 49% between 1970 and 2006. ( 97% for lead, 52% for volatile organic
compounds, 50% for carbon monoxide, 47% for sulfur dioxide, 33% for NOx, and 28% for
suspended particulate matter).
5. Bad news: According to the EPA, in 2006, about one in three Americans lived in a area where
the air was unhealthy to breathe for at least part of the year.
B. Outdoor air pollution in the U.S. has been reduced since 1970, however, scientists point out several
deficiencies in the Clean Air Act; they include:
1. The U.S. continues to mostly rely on cleanup rather than prevention.
2. The U.S. Congress has failed to increase fuel-efficiency standard for cars, SUVs, ad light trucks.
3. Regulation of emissions from motorcycles and two-cycle gasoline engines remains inadequate.
4. There is little or no regulation of air pollution from oceangoing ship in American ports.
5. Airports are exempt from any air pollution regulations.
6. The Act does not regulate emissions f of carbon dioxide.
7. Urban ozone levels are still too high in many areas.
8. The Act has failed to deal seriously with indoor air pollution.
9. There is a need for better enforcement of the Clean Air Act.
C. Allowing producers of air pollutants to buy and sell government air pollution allotments in the
marketplace can help reduce emissions.
1. The Clean Air Act of 1990 allows an emissions trading policy that permits companies to buy and
sell SO2 pollution rights.
2. This cap-and-trade approach may be an improvement over command-and-control as long as it
reduces SO2 emissions. The cap would gradually be lowered.
3. These pollution credits may be purchased by anyone and then not used if they so desire.
4. Between 1990 and 2006 this scheme reduced SO2 emissions by 53% in the U.S.
5. Emissions trading is being tried for NOx, and may someday be used to reduce CO2 emissions.
D. There are a number of ways to prevent and control air pollution from coal-burning facilities and
motor vehicles. See pages 491–493.
1. Coal plants use output approaches like electrostatic precipitators which use magnets to attract
negatively charged particles, and wet scrubbers which use water mists to trap and collect
pollutants.
2. Input approaches include reduced sulfur coal, coal gasification and fluidized-bed combustion.
3. Between 1980 and 2002, emissions of sulfur dioxides form U.S. electric power plant decreased
by 40% and NOx by 30% and soot by 75%.
E. There is a need to focus on preventing air pollution of all types.
1. At present there is an output approach to controlling pollution.
2. We need to shift focus to preventing air pollution before it is created.