Air Pollution

Air PollutionAir Pollution

The AtmosphereThe Atmosphere

• This is our protective blanket of gasses.

– 78% Nitrogen– 21% Oxygen

– .03% Carbon Dioxide CO2

– .01% Ozone 03

Atmospheric GasesAtmospheric Gases

Fig. 19-2, p. 440

Atmospheric pressure (millibars)

Temperature

Thermosphere

Pressure

Mesopause

Heating via ozoneMesosphere

Stratopause

Alt

itu

de

(kil

om

eter

s)

Stratosphere Alt

itu

de

(mil

es)

Tropopause

Ozone “layer”

Heating from the earthHeating from the earthTroposphere

Temperature (˚C)

Pressure = 1,000 millibars at ground level

(Sea level)

The Atmosphere - LayersThe Atmosphere - Layers

• Troposphere– Layer in which we live– Most weather occurs here– 90% of the gasses are here– 78% nitrogen, 21% oxygen– 0-6 mile above N and S Pole

• Mount Everest is 5.3 miles tall

– 0-10 miles above equator– Temperature decreases with

altitude until the next layer is reached

• Stratosphere– 6-31 miles in altitude– Calm– Air traffic due to lack of

weather– Temperature increases with

altitude– Ozone layer (oxygen is

converted to O3 by lightning and/or sunlight)

– 99% of ultraviolet radiation (especially UV-B) is absorbed by the stratosphere


• Mesosphere– 30 to 50 miles in altitude– Temperature decreases

with increasing altitude– Temperatures in the

mesopause (top of the mesosphere) are the coldest on Earth – approx. -100˚C (-148˚F)

– Above airplane heights and below orbital heights, thus it is poorly understood

• Thermosphere– 50 to 310 miles in altitude– Biggest of all layers– Temperature increases

with altitude– Very high temperatures

1,500 °C (2,730 °F) to 2,500 °C (4,530 °F) but little heat is transferred because of the space between the gas particles

– International Space Station flies in this layer


• Exosphere– 310 miles to space– Upper most layer of the

atmosphere– Only light elements exist

here, mainly Hydrogen

To the right is a scale representation of the atmospheric layers:

• Purple = Exosphere• Blue = Thermosphere• Green = Mesosphere• Yellow = Stratosphere• Red = Troposphere

OzoneOzone

• How much of our atmosphere is ozone?

• Ozone that surrounds the earth 12-35 miles above the earth is our first line of defense of the sun’s ultraviolet radiation.– This radiation can cause sunburn, skin

cancer, cataracts, …

• Ozone is constantly created and destroyed

What Happens to Solar Energy What Happens to Solar Energy Reaching the Earth?Reaching the Earth?

• Solar energy flowing through the biosphere warms the atmosphere, evaporates and recycles water, generates winds and supports plant growth.

Figure 3-8Figure 3-8

The Natural Greenhouse EffectThe Natural Greenhouse Effect• Three major factors shape the earth’s

climate:– The sun.– Greenhouse effect that warms the earth’s lower

troposphere and surface because of the presence of greenhouse gases.

– Oceans store CO2 and heat, evaporate and receive water, move stored heat to other parts of the world.

– Natural cooling process through water vapor in the troposphere (heat rises).

Greenhouse EffectGreenhouse Effect

• This “greenhouse effect” is vital for our survival. Without heat trapping gasses our planet would be cold and lifeless.

• The gasses act like a car that gets hot inside.

Major Greenhouse GasesMajor Greenhouse Gases• The major greenhouse gases in the lower

atmosphere are water vapor, carbon dioxide, methane, nitrous oxide, ozone, and CFCs.– These gases have always been present in the

earth’s troposphere in varying concentrations.– Fluctuations in these gases, plus changes in solar

output are the major factors causing the changes in tropospheric temperature over the past 400,000 years.

Major Greenhouse Major Greenhouse GasesGases

• Increases in average concentrations of three greenhouse gases in the troposphere between 1860 and 2004, mostly due to fossil fuel burning, deforestation, and agriculture.


PAST CLIMATE AND THE PAST CLIMATE AND THE GREENHOUSE EFFECTGREENHOUSE EFFECT

• Over the past 900,000 years, the troposphere has experienced prolonged periods of global cooling and global warming.

• For the past 1,000 years, temperatures have remained fairly stable but began to rise during the last century.

PAST CLIMATE AND THE PAST CLIMATE AND THE GREENHOUSE EFFECTGREENHOUSE EFFECT


How Do We Know What How Do We Know What Temperatures Were in the Past?Temperatures Were in the Past?

• Scientists analyze tiny air bubbles trapped in ice cores learn about past:– troposphere

composition. – temperature trends.– greenhouse gas

concentrations.– Solar output, snowfall,

and forest fire activity.


How Do We Know What How Do We Know What Temperatures Were in the Past?Temperatures Were in the Past?

• In 2005, an ice core showed that CO2 levels in the troposphere are the highest they have been in 650,000 years.


Greenhouse EffectGreenhouse Effect

• If the gasses in the atmosphere become increased beyond “normal” the temperature of the earth can increase.

• An increase in temperature can change the climate cycles.– Ice caps melt, drought, floods, change in

temperature…– Effects the environment as well

• What are some effects if the above happens?

ControversyControversy

• CO2 levels are increasing due to human activity – no controversy

• What does that mean? - controversy– 97% of climate scientists agree that this leads

to global warming– 53% of Americans believe global warming is

real– 87% of Europeans believe global warming is

a serious concern

Data can be manipulatedData can be manipulated

From NOAAFrom NOAA

EFFECTS OF GLOBAL EFFECTS OF GLOBAL WARMINGWARMING

• Between 1979 and 2005, average Arctic sea ice dropped 20% (as shown in blue hues above).


Rising Sea LevelsRising Sea Levels

• During this century rising seas levels are projected to flood low-lying urban areas, coastal estuaries, wetlands, coral reefs, and barrier islands and beaches.


Rising Sea LevelsRising Sea Levels

• If seas levels rise by 9-88cm during this century, most of the Maldives islands and their coral reefs will be flooded.


Changing Ocean CurrentsChanging Ocean Currents

• Global warming could alter ocean currents and cause both excessive warming and severe cooling. Figure 20-12Figure 20-12

CLIMATE CHANGE AND HUMAN CLIMATE CHANGE AND HUMAN ACTIVITIESACTIVITIES

• Evidence that the earth’s troposphere is warming, mostly because of human actions:– The 20th century was the hottest century in the past

1000 years.– Since 1900, the earth’s average tropospheric

temperature has risen 0.6 C°.– Over the past 50 years, Arctic temperatures have

risen almost twice as fast as those in the rest of the world.

– Glaciers and floating sea ice are melting and shrinking at increasing rates.


• A warmer troposphere can decrease the ability of the ocean to remove and store CO2 by decreasing the nutrient supply for phytoplankton and increasing the acidity of ocean water.

• Global warming will lead to prolonged heat waves and droughts in some areas and prolonged heavy rains and increased flooding in other areas.


• In a warmer world, agricultural productivity may increase in some areas and decrease in others.

• Crop and fish production in some areas could be reduced by rising sea levels that would flood river deltas.

• Global warming will increase deaths from:– Heat and disruption of food supply.– Spread of tropical diseases to temperate regions.– Increase the number of environmental refugees.

DEALING WITH GLOBAL DEALING WITH GLOBAL WARMINGWARMING

• Climate change is such a difficult problem to deal with because:– The problem is global.– The effects will last a long time.– The problem is a long-term political issue.– The harmful and beneficial impacts of climate

change are not spread evenly.– Many actions that might reduce the threat are

controversial because they can impact economies and lifestyles.


• Air Pollutant is defined as any substance in the air that is concentrated enough to harm living things or do damage to man-made objects.

• The EPA regulates (tries) pollution emissions from combustion by factories and machines.

Human Actions and Our Human Actions and Our EnvironmentEnvironment

• When the human population was low, there was very little impact to the environment.– Wind, rain, and time were the natural air

cleaners.

• As the human population increased, time could not clean the air fast enough.


• The human impact has changed three major ecosystem cycles.

1. The chemical cycles– Carbon Cycle– Nitrogen Cycle– Sulfur Cycle

– By adding more chemicals we slow down the cycle


2. The energy cycles• Conservation of energy• Energy from fossil fuels is used faster that

replaced

3. Biodiversity is reduced• Farms reduce the plant biodiversity with a single

crop, and kill animals with chemicals


• Primary pollutants – released directly into the atmosphere– Ex) nitrogen oxides (NOx), sulfur oxides (SOx),

methane (CH4), dust, Chlorofluorocarbons (CFCs)

• Causes of Primary Pollutants – factories, cars, wind and soil, volcanoes, forest fires, pollen, decaying plants, salt particles from the sea, and refrigerants.

Air PollutionAir Pollution• Secondary pollutants – Form when

primary pollutants react.– Ex) ozone, smog, and acid rain

Air Pollutants – Carbon OxidesAir Pollutants – Carbon Oxides• Carbon monoxide (CO) is a highly toxic gas that

forms during the incomplete combustion of carbon-containing materials.

• 93% of carbon dioxide (CO2) in the troposphere occurs as a result of the carbon cycle.

• 7% of CO2 in the troposphere occurs as a result of human activities (mostly burning fossil fuels).

• It is not regulated as a pollutant under the U.S. Clean Air Act.

Carbon CycleCarbon Cycle

• The ocean is the largest carbon sink.

• The process of CO2 being removed from the atmosphere and stored by a sink is called sequestration.

Ocean AcidificationOcean Acidification

• Dissolving CO2 in seawater increases the hydrogen ion (H+) concentration in the ocean, and thus decreases ocean pH.

• Between 1751 and 1994 surface ocean pH is estimated to have decreased from approximately 8.25 to 8.14, representing an increase of approaching 30% in acidity.

The Nitrogen Cycle: The Nitrogen Cycle:

Steps in Nitrogen CycleSteps in Nitrogen Cycle• Nitrogen Fixation

– Lightning (N2 NO3)

– Bacteria (N2 NH4+)

• Nitrification (NH4+ NO2- (nitrite) NO3-(nitrates))

• Assimilation (NO3-(nitrates) converted to amino acids, DNA, chlorophyll)

• Ammoniafication (wastes and decaying organisms broken down into NH4

+)

• Denitrification (nitrites are changed to N2 by anaerobic bacteria)

Air Pollutants – Nitrogen OxidesAir Pollutants – Nitrogen Oxides

• The atmosphere is the largest nitrogen sink, storing nitrogen in the form of N2.

• NO2 reacts with water vapor in the air to form nitric acid (HNO3) and nitrate salts (NO3

-) which are components of acid deposition.

Human Influence on Nitrogen Human Influence on Nitrogen CycleCycle

• Fossil fuel combustion,

• Use of artificial nitrogen fertilizers,

• Release of nitrogen in wastewater

• At high temps, N2 reacts with O2 to form NOx.

• Gives brown color to smog

• Photochemical smog – nitrogen and light form “bad” ozone.

Air Pollutants – Sulfur OxidesAir Pollutants – Sulfur Oxides

• Naturally occurring– Volcanoes

• Burning of coal, oil, gasoline

• Cause Lung damage, asthma, and bronchitis

• Sulfur can be removed from smoke by wet scrubbers in factories

• Largest sulfur sink is sedimentary rocks

Air Pollutants – Sulfur OxidesAir Pollutants – Sulfur Oxides

• Sulfur dioxide (SO2) and sulfuric acid:

– About one-third of SO2 in the troposphere occurs naturally through the sulfur cycle.

– Two-thirds come from human sources, mostly combustion (S+ O2 SO2) of sulfur-containing coal and from oil refining and smelting of sulfide ores.

– SO2 in the atmosphere can be converted to sulfuric acid (H2SO4) and sulfate salts (SO4

2-) that return to earth as a component of acid deposition.

The Sulfur CycleThe Sulfur Cycle


Air Pollutants - VOCsAir Pollutants - VOCs• Volatile organic compounds (VOCs):

– Organic compounds (mostly hydrocarbons) that exist as gases in the air

– Ex) incomplete combustion of gasoline, methane– About two thirds of global methane emissions

comes from human sources.– Can be natural (methane and terpenes) or man-

made (trichlorethylene (TCE), benzene, CFCs and vinyl chloride).

• Long-term exposure to benzene can cause cancer, blood disorders, and immune system damage.

Air Pollutants - OzoneAir Pollutants - Ozone

• VOC + NOx + Sunlight = Ozone (O3)

– It can • Cause and aggravate respiratory illness.• Can aggravate heart disease.• Damage plants, rubber in tires, fabrics, and paints.

• Ozone (O3):

– “bad” ozone - found in troposphere– Is a highly reactive gas that is a major

component of photochemical smog.

Atmospheric OzoneAtmospheric Ozone

• Lightning and Ultraviolet light creates ozone, but there are a variety of things that can destroy it faster. THEY STAY AROUND LONGTERM

• CFC – Chlorofluorocarbons react with an oxygen atom to break down O3 to O2.

• 1 chlorine can destroy 100,000 ozone molecules• CFC’s come from refrigeration and aerosol cans.• As ozone is broken down, the ozone layer gets

thinner. – This radiation that gets through can cause sunburn,

skin cancer, cataracts, …

Fig. 20-18, p. 486

A free oxygen atom pulls the oxygen atom off the chlorine monoxide molecule to form O2.

Ultraviolet light hits a chlorofluorocarbon (CFC) molecule, such as CFCl3, breakingoff a chlorine atom and leaving CFCl2. Sun

Repeated many times

The chlorine atom and the oxygen atom join to form a chlorine monoxide molecule (ClO).

Summary of ReactionsCCl3F + UV Cl + CCl2FCl + O3 ClO + O2

Cl + O Cl + O2

UV radiation

The chlorine atom attacksan ozone (O3) molecule, pulling an oxygen atom offit and leaving an oxygen molecule (O2).

Once free, the chlorine atom is off to attack another ozone moleculeand begin the cycle again.

Cl

Atmospheric OzoneAtmospheric Ozone

• Where is the ozone the thinnest?

New Index

Air Pollutants – ParticulatesAir Pollutants – Particulates

• Suspended particulate matter (SPM):– Consists of a variety of solid particles and

liquid droplets small and light enough to remain suspended in the air.• Light enough to float in air• Dust, lead, mercury, radon• Get in lungs, stain buildings, reduce

visibility

URBAN OUTDOOR AIR URBAN OUTDOOR AIR POLLUTIONPOLLUTION

• Industrial smog is a mixture of sulfur dioxide, droplets of sulfuric acid, and a variety of suspended solid particles emitted mostly by burning coal.– In most developed countries where coal and

heavy oil is burned, industrial smog is not a problem due to reasonably good pollution control or with tall smokestacks that transfer the pollutant to rural areas.

Fig. 19-3, p. 442

Primary Pollutants

CO CO2Secondary Pollutants

SO2 NO NO2

Most hydrocarbons SO3

Most suspended particles HNO3

H2O2 O3 PANs

Most NO3– and SO4

2– salts

Sources Natural Stationary

Mobile

H3SO4

ACID DEPOSITIONACID DEPOSITION

• Sulfur dioxides, nitrogen oxides, and particulates can react in the atmosphere to produce acidic chemicals that can travel long distances before returning to the earth’s surface.– Tall smokestacks reduce local air pollution but

can increase regional air pollution.

Acid DepositionAcid Deposition

• AKA Acid Rain• Rain cleans the air,

but pollutes the water.• Normal pH is 6.6

Acid Rain is about 4.3• Plants like to grown in

soil with a pH of 6-7• What happens to the

plants?

Fig. 19-6, p. 448

WindTransformation to sulfuric acid (H2SO4) and nitric acid (HNO3)

Windborne ammonia gas and particles of cultivated soil partially neutralize acids and form dry sulfate and nitrate salts

Wet acid depostion (droplets of H2SO4 and HNO3 dissolved in rain and snow)

Nitric oxide (NO)Sulfur dioxide (SO2) and NO

Dry acid deposition (sulfur dioxide gas and particles of sulfate and nitrate salts)

Acid fogFarm

OceanLakes in deep Lakes in deep

soil high in soil high in limestone are limestone are

bufferedbuffered

Lakes in shallow Lakes in shallow soil low in limestone soil low in limestone

become acidicbecome acidic

ACID RAIN


• pH measurements in relation to major coal-burning and industrial plants.



• Air pollution is one of several interacting stresses that can damage, weaken, or kill trees and pollute surface and groundwater.


Factors Influencing Levels of Factors Influencing Levels of Outdoor Air PollutionOutdoor Air Pollution

• Outdoor air pollution can be reduced by:– settling out, precipitation, sea spray, winds,

and chemical reactions.

• Outdoor air pollution can be increased by:– urban buildings (slow wind dispersal of

pollutants), mountains (promote temperature inversions), and high temperatures (promote photochemical reactions).

Geography can effect pollution Geography can effect pollution concentrations.concentrations.

Topography and PollutionTopography and Pollution

• Mountainous areas tend to trap pollution

• Flat areas tend to allow pollution to disperse

• Forest Fires in the Los Angeles area.

• Winds carry the smoke across the ocean.

• Wind can clean the air, but it can also spread it somewhere else.

Geography can effect air pollution.Geography can effect air pollution.

Temperature InversionTemperature Inversion

• Cold air is more dense. Sometimes when it sinks below the warm air, it brings the pollution with it.

Temperature InversionsTemperature Inversions

• Cold, cloudy weather in a valley surrounded by mountains can trap air pollutants (left).

• Areas with sunny climate, light winds, mountains on three sides and an ocean on the other (right) are susceptible to inversions.


• Rising smoke in Lochcarron, Scotland forms a ceiling over the valley due to a temperature inversion

Great Smog of 1952Great Smog of 1952• London • Thousands died b/c of smog

(respiratory illness)

• Results: – Caused evaluation of smog

effects of health– Passed the Clean Air Act of

1956 (UK)

How does air quality effect me?How does air quality effect me?

• Asthma• Emphysema• Allergies• Heart disease• Drink polluted water• Colds• Pneumonia

Law – Clean Air ActLaw – Clean Air Act• 1963 - first passage • 1970, 1977 and 1990 - amended• Involves EPA• Sets standards for acceptable levels of

sulfur oxides, nitrogen oxides, ozone, carbon monoxide, hydrocarbons, lead, & cut out CFCs

• Provides pollution credits for industries that utilize pollution-control devices+

• Bush administration relaxed rules

PREVENTING AND REDUCING PREVENTING AND REDUCING AIR POLLUTIONAIR POLLUTION

• The Clean Air Acts in the United States have greatly reduced outdoor air pollution from major pollutants:– Carbon monoxide– Nitrogen oxides– Sulfur dioxides– Suspended particulate matter


• Deficiencies in the Clean Air Act:– The U.S. continues to rely on cleanup rather

than prevention.– The U.S. Congress has failed to increase fuel-

efficiency standards for automobiles.– Regulation of emissions from motorcycles and

two-cycle engines remains inadequate.– There is little or no regulation of air pollution

from oceangoing ships in American ports.


– Airports are exempt from many air pollution regulations.

– The Act does not regulate the greenhouse gas CO2.

– The Act has failed to deal seriously with indoor air pollution.

– There is a need for better enforcement of the Clean Air Act.

National Ambient Air Quality National Ambient Air Quality Standards (NAAQS)Standards (NAAQS)

• Sets acceptable concentrations for 6 “criteria” pollutants that:

– Threaten public health/the environment over broad areas (non-point)

– Are emitted in large quantities

– CO, Pb, Nitrogen Oxides, Ozone, Particulate Matter and Sulfur Dioxides

What kind of things are being done to What kind of things are being done to control the pollution internationally?control the pollution internationally?

• Kyoto Protocol• is a protocol to the United Nations Framework

Convention on Climate Change (UNFCCC), aimed at fighting global warming

• The United Nations Framework Convention on Climate Change (UNFCCC) is an international environmental treaty with the goal of achieving the "stabilization of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system.“

National ParticipationNational Participation

Solutions: Solutions: Reducing Outdoor Air PollutionReducing Outdoor Air Pollution

• There are a of ways to prevent and control air pollution from motor vehicles.– Because of the Clean Air Act, a new car today

in the U.S. emits 75% less pollution than did pre-1970 cars.

– There is an increase in motor vehicle use in developing countries and many have no pollution control devices and burn leaded gasoline.

Solutions: Solutions: Reducing Outdoor Air PollutionReducing Outdoor Air Pollution

• There are a couple of ways to prevent and control air pollution from coal-burning facilities.– Electrostatic precipitator: are used to attract

negatively charged particles in a smokestack into a collector.

– Wet scrubber: fine mists of water vapor trap particulates and convert them to a sludge that is collected and disposed of usually in a landfill.

Electrostatic PrecipitatorElectrostatic Precipitator• Can remove 99% of particulate

matter• Does not remove hazardous

ultrafine particles.• Produces toxic dust that must be

safely disposed of.• Uses large amounts of electricity


Wet ScrubberWet Scrubber

• Can remove 98% of SO2 and particulate matter.

• Not very effective in removing hazardous fine and ultrafine particles.


INDOOR AIR POLLUTIONINDOOR AIR POLLUTION• Indoor air pollution usually is a greater threat

to human health than outdoor air pollution.

• According to the EPA, the four most dangerous indoor air pollutants in developed countries are:– Tobacco smoke.– Formaldehyde.– Radioactive radon-222 gas.– Very small fine and ultrafine particles.

Indoor PollutionIndoor PollutionPollutant• Ammonia• Arsenic

• Asbestos • Bacteria• Benzene/Gasoline• Carbon Monoxide

Where Found

• Cleaning Products• Smoking/

pesticides/rodent poison

• Insulation• Damp building• Gasoline• Wood burning

fireplace, tobacco smoke, kerosene, automobiles, natural gas

Health Effect• Respiratory Irritant• Toxic / carcinogen

• Lung diseases• Bacterial infections• Respiratory irritant• Headaches,

drowsiness, dizziness, confusion, nausea, death

Pollutant

• Chloroform

• Fiberglass

• Formaldehyde

• Fungus/Mold

• Lead particulate

Where Found

• Chlorine treated water

• Tables, insulation, skateboards

• Furniture stuffing, particle board, fiber board, foam insulation, carpeting

• Air systems, damp buildings

• Paint particulates, exhaust from leaded gasoline

Health Effect• Cancer

• Respiratory and skin irritant

• Nasal/lung cancer, asthma, eye/nose/ throat irritant

• Respiratory irritant

• Impaired development, clumsiness, memory loss, anemia

Pollutant

• Mercury

• Methane/Propane

• Tobacco Smoke

• Pesticides

Where Found

• Fungicides, old thermometers/ thermostats

• Natural gas leaks / sewer backup

• Cigarettes, cigars, pipes

• Sprays, strips, outdoor air

Health Effect• Damages nervous

system, Cancer

• Headaches, fatigue, nausea, confusion,

• Cancer, heart disease, respiratory disease, ear infections

• Central nervous system/ Kidney / liver damage

Pollutant

• Radon

• Trichloroethane

• VOCs

Where Found

• Radioactive soil/foundations, Uranium deposits, radioactive well water

• Aerosol sprays

• Tobacco combustion, burned food, paints, varnishes, cleaning products

Health Effect• Lung cancer, lung

tissue damage

• Dizziness, irregular breathing

• Respiratory irritant, weakened immune system

Methods of prevention or clean-upMethods of prevention or clean-up• Improved Ventilation

• Tobacco smoke reduction methods

• Legislative measures

• Alternative materials

• Control temperature and humidity

• Alternative pest control

• Maintenance of appliances and filtering systems

Case Study: Radioactive RadonCase Study: Radioactive Radon

• Radon-222, a radioactive gas found in some soils and rocks, can seep into some houses and increase the risk of lung cancer.

Sources and paths of entry Sources and paths of entry for indoor radon-222 gasfor indoor radon-222 gas.


Chloroform

Benzo--pyrene

Styrene

Radon-222

Methylene Chloride

Tobacco Smoke

Carbon Monoxide

Asbestos

Nitrogen Oxides

1, 1, 1-Trichloroethane

Particulates

FormaldehydeTetrachloroethylene

Para-dichlorobenzene

Fig. 19-11, p. 453

Air Pollution

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