© 2011 Pearson Education, Inc. This lecture will help you understand: Stratospheric ozone depletion Acidic deposition and consequences Indoor air pollution

© 2011 Pearson Education, Inc.

This lecture will help you understand:

• Stratospheric ozone depletion

• Acidic deposition and consequences

• Indoor air pollution and solutions


Layers of the Atmosphere

Temperature Changes through the layers


The atmosphere’s four layers

• Atmospheric layers have different- Temperatures- Densities- Composition


Synthetic chemicals deplete stratospheric ozone• Ozone layer = ozone in the lower stratosphere

- Blocks incoming ultraviolet (UV) radiation- Protecting life from radiation’s damaging effects

• Ozone-depleting substances = human-made chemicals that destroy ozone by splitting its molecules apart

• Halocarbons = human-made compounds made from hydrocarbons with added chlorine, bromine, or fluorine

• Chlorofluorocarbons (CFCs) = a halocarbon used as refrigerants, in fire extinguishers, in aerosol cans, etc.- Releases chlorine atoms that split ozone


CFCs destroy ozone

• CFCs are inert (don’t react)• CFCs remain in the

stratosphere for a century• UV radiation breaks CFCs

into chlorine and carbon atoms

• The chlorine atom splits ozone

• Ozone hole = decreased ozone levels over Antarctica

One chlorine atom can destroy 100,000 ozone molecules


The Antarctic ozone hole• High-altitude polar stratospheric clouds form during the

dark, frigid winter• Nitric acid in clouds splits chlorine off of CFCs

- A polar vortex (swirling winds) traps chlorine- UV radiation in September (spring) sunshine dissipates

the clouds and releases the chlorine

- The chlorine destroys the ozone

- December’s warmer air shuts down the polar vortex

- Ozone-poor air diffuses, while ozone-rich air enters


The decrease of ozone amounts in the upper atmosphere above Antarctica and nearby regions between 1980 and 2000 has caused an increase in the amount of ultraviolet radiation striking the Earth


Sunburn

Skin types. Phototype/Ethnicity UV-sensitivity Sunburn/tan

I/White Caucasian Extremely sensitive Always burns, never tans

II/White Caucasian Very sensitive Burns readily, tans slowly and with difficulty

III/White Caucasian Moderately sensitive Can burn after high exposure, tans slowly

IV/White Caucasian, often south Mediterranean Relatively tolerant Burns rarely, tans easily V/Brown, Asian/Middle Eastern Variable Can burn easily, difficult to assess as

pigment is already present VI/Black, Afro-Caribbean Relatively insensitive Rarely burns


Ultraviolet (UV) photons harm the DNA molecules of living organisms in different ways. In one common damage event, adjacent bases bond with each other, instead of across the “ladder.” This makes a bulge, and the distorted DNA molecule does not function properly


Skin Cancer


Immune System

Cold sores caused by reactivation of latent herpes simplex virus following exposure to solar UV-B radiation

UVB radiation appears to reduce the effectiveness of the immune system – in the case of cold sores it can no longer keep the virus Herpes simplex under control which results in re-activation of the infection.

UVB radiation appears to reduce the effectiveness of the immune system – in the case of cold sores it can no longer keep the virus Herpes simplex under control which results in re-activation of the infection.


Cataracts

Cataracts occur when there is a buildup of protein in the lens that makes it cloudy


Overexposure to ultraviolet radiation can change the flowering times of some kinds of plants and therefore will affect the animals that depend on them.


Effects on Ecosystems

UV radiation influences the biological productivity of oceans, including the production of gases at their surfaces and their subsequent transfer to the atmosphere.

Protective molecules produced by plants in response to UV radiation include the red pigments seen in lettuces (left panel), while those shielded from UV are mostly green.


The Montreal Protocol• Montreal Protocol = 196 nations agreed to cut CFC

production in half by 1998• Follow-up agreements deepened cuts, advanced

timetables, and addressed other ozone-depleting chemicals- Industry shifted to safer, inexpensive, and efficient

alternatives• Challenges still face us

- CFCs will remain in the stratosphere for a long time- Nations can ask for exemptions to the ban


The Montreal Protocol is a success

• It is considered our biggest environmental success story• Research developed rapidly, along with technology• Policymakers included industry in helping solve the

problem• Implementation of the plan allowed an adaptive

management strategy - Strategies responded to new scientific data,

technological advances, and economic figures• The Montreal Protocol can serve as a model for

international environmental cooperation


Protecting the ozone layer

International agreements reduced ozone-depleting substances

The hole in the ozone has stopped growing


Criteria pollutants: tropospheric ozone

• Tropospheric ozone (O3) a colorless gas with a strong odor “ground-level ozone”- Results from interactions of sunlight, heat, nitrogen

oxides, and volatile carbon-containing chemicals- A secondary pollutant; A major component of smog - Participates in reactions that harm tissues and cause

respiratory problems; The pollutant that most frequently exceeds EPA standards


Ground-level ozone formation


Effects of Ozone Air Pollution on Plants

• Ground-level ozone causes more damage to plants than all other air pollutants combined.

• classical symptoms of ozone injury and shows how ozone affects yield of several major crops.


UV radiation and the biosphere

UV-B impairs photosynthesis in many species. Overexposure to UV-B reduces size, productivity, and quality in many of the crop plant species that have been studied (among them, many varieties of rice, soybeans, winter wheat, cotton, and corn).

Similarly, overexposure to UV-B impairs the productivity of phytoplankton in aquatic ecosystems.

UV-B increases plants’ susceptibility to disease.

Scientists have found it affects enzyme reactions that conduct fundamental biological functions, it impairs cellular division in developing sea urchin eggs, and

it changes the movements and orientation of tiny organisms as they move through ocean waters. Since some species are more vulnerable to UV-B than others, an increase in UV-B exposure has the potential to cause a shift in species composition and diversity in various ecosystems.

Because UV-B affects organisms that move nutrients and energy through the biosphere, we can expect changes in their activities to alter biogeochemical cycles. For example, reducing populations of phytoplankton would significantly impact the world’s carbon cycle, because phytoplankton store huge amounts of carbon in the ocean.


Ozone and Humans

• Low concentrations of ground-level ozone can irritate the eyes, nose and throat.

• Ozone can also irritate the lung airways, and make them red and swollen (inflammation).

• It can trigger more serious illnesses, including coughing, asthma, bronchitis, chest pain, breathing difficulties during outdoor exercise and greater susceptibility to lung illnesses like pneumonia. Prolonged exposure can damage lung tissue, cause premature aging of the lungs and contribute to chronic lung disease.

• Children, the elderly and people with impaired lung function are considered to be most at risk.

• Even healthy people and athletes who are active outdoors can be affected when ozone

levels are high.


Acid deposition

• Acid deposition is another transboundary issue• Acidic deposition = the deposition of acid, or acid-

forming pollutants from the atmosphere onto Earth’s surface

• Acid rain = precipitation containing acid- Rain, snow, sleet, hail

• Atmospheric deposition = the wet or dry deposition on land of pollutants (mercury, nitrates, organochlorines)- From automobiles, electric utilities, industrial facilities


Burning fossil fuels produces acid rain

• Burning fossil fuels releases sulfur dioxide and nitrogen oxides- These compounds react with water, oxygen, and

oxidants to form sulfuric and nitric acids


Impacts of acid deposition• Nutrients are leached from topsoil• Soil chemistry is changed• Metal ions (aluminum, zinc, etc.) are converted into

soluble forms that pollute water• Affects surface water and kills fish• Damages agricultural crops• Erodes stone buildings, corrodes cars, erases writing on

tombstones


pH of precipitation in the U.S.

Many regions of acidification are downwind of major sources of pollution

• The acid-neutralizing capacity of soil, rock, or water impacts the severity of acid rain’s effects


We have begun to address acid deposition

• Reducing acid deposition involves reducing the pollution that contributes to it

• The Clear Air Act of 1990 established an emissions trading program for sulfur dioxide- Benefits outweighed costs 40:1

• New technologies such as scrubbers have helped• Acid deposition is worse in the developing world

- Especially in China, which burns coal in factories lacking pollution control equipment


Indoor air pollution

• Indoor air pollution = in workplaces, schools, and homes- Health effects are greater than from outdoor pollution

• The average U.S. citizen spends 90% of the time indoors- Exposed to synthetic materials that have not been

comprehensively tested• Being environmentally prudent can make it worse

- To reduce heat loss and improve efficiency, ventilation systems were sealed off

- Windows do not open, trapping pollutants inside


Indoor air pollution in the developing world

• Stems from burning wood, charcoal, dung, crop wastes with little to no ventilation

• Fuel burning pollution causes 1.6 million deaths/year- Soot and carbon monoxide- Pneumonia, bronchitis, lung cancer, allergies,

cataracts, asthma, heart disease, etc.


Tobacco smoke and radon

• The most dangerous indoor pollutants in developed nations

• Secondhand smoke from cigarettes is very dangerous - Contains over 4,000 chemical compounds- Causes eye, nose, and throat irritation- Smoking has declined in developed nations

• Radon causes 21,000 deaths a year in the U.S.- A radioactive gas resulting from natural decay of rock,

soil, or water that can seep into buildings - New homes are being built that are radon resistant


Radon risk across the U.S.


VOCs pollute indoor air

• The most diverse group of indoor air pollutants

- Released by everything from plastics and oils to perfumes and paints

- Most VOCs are released in very small amounts• Unclear health implications due to low concentrations• Formaldehyde leaking from pressed wood and insulation

irritates mucous membranes and induces skin allergies• Pesticides seep through floors and walls

- Are brought in on shoe soles


Sources of indoor air pollution


Living organisms can pollute indoors

• Dust mites and animal dander worsen asthma• Fungi, mold, mildew, airborne bacteria cause allergies,

asthma, other respiratory ailments, and diseases• Building-related illness = a sickness produced by indoor

pollution• Sick building syndrome = a sickness produced by

indoor pollution with general and nonspecific symptoms- Reduced by using low-toxicity building materials and

good ventilation


We can reduce indoor air pollution

• In developed countries:- Use low-toxicity materials, limit use of plastics and

treated wood, monitor air quality, keep rooms clean- Provide adequate ventilation- Limit exposure to known toxicants- Test homes and offices and use CO detectors

• In developing countries:- Dry wood before burning- Cook outside- Use less-polluting fuels (natural gas)


Conclusion

• Indoor air pollution is a potentially serious health threat- We can significantly minimize risks

• Outdoor air pollution has been addressed by government legislation and regulation in developed countries

• Reduction in outdoor air pollution represents some of the greatest strides in environmental protection- There is still room for improvement, especially in

developing countries


QUESTION: Review

The major component of Earth’s atmosphere is:

a) Nitrogen gas

b) Oxygen gas

c) Argon gas

d) Water vapor


QUESTION: Review

Ozone in the _________ is a pollutant, but in the ______ is vital for life.

a) Stratosphere, troposphere

b) Troposphere, stratosphere

c) Troposphere, tropopause

d) Stratosphere, thermosphere


QUESTION: Review

With convective circulation:

a) Less dense, cooler air rises

b) Denser, warmer air rises

c) Less dense, warmer air rises

d) Denser, cooler air rises


QUESTION: Review

If you were on a sailing ship going from the United States to Europe, you would want to be in the area of the _____.

a) Doldrums

b) Trade winds

c) Westerlies

d) Polar cell


QUESTION: Review

The Clean Air Act does all of the following, EXCEPT:

a) Forbid emissions trading

b) Provide funds for pollution-control research

c) Allow citizens to sue violators

d) Set standards for air quality


QUESTION: Review

Which criteria pollutant is highly reactive, foul smelling, and has a reddish brown color?

a) Sulfur dioxide

b) Nitrogen dioxide

c) Tropospheric ozone

d) Carbon monoxide


QUESTION: Review

Why is the Montreal Protocol considered our greatest environmental success story?

a) It has stopped global warming.

b) It decreased criteria pollutants.

c) It successfully stopped ozone depletion.

d) It slowed acid deposition.


QUESTION: Viewpoints

Think of a major city near you. Do you think drivers should have to pay to drive downtown?

a) Yes, if mass transit is available.

b) Yes, but only charge people who do not live in the downtown area.

c) No, it’s my right to drive wherever I want to.

d) I don’t care, because I don’t own a car.


QUESTION: Viewpoints

Should the government be able to force industries to put pollution-control devices on their factories?

a) Yes, I don’t want to be exposed to pollution.

b) Yes, only if the people in the area agree.

c) No, let the factory owner decide.

d) No, in these tough economic times, we need to leave businesses alone.


QUESTION: Interpreting Graphs and Data

What does this graph show about the stratosphere?

a) It contains the most ozone.

b) It is a very thin layer.

c) Temperature decreases with increasing altitude.

d) Temperature is not affected with increasing altitude.


QUESTION: Interpreting Graphs and Data

Which conclusion can you draw from this graph?

a) Even though population and consumption increased, emissions have decreased.

b) Emissions have decreased but population has increased.

c) People have increased emissions, but only slightly.

d) The United States no longer needs the Clean Air Act.

Documents

© 2011 Pearson Education, Inc. This lecture will help you understand: Stratospheric ozone depletion Acidic deposition and consequences Indoor air pollution