Transcript Pollution - HCC Learning Web

Environmental Science
A Study of Interrelationships
Eleventh Edition
Enger & Smith
Chapter 16
Air Quality Issues
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Air Quality Issues
Outline
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The Atmosphere
Pollution of the Atmosphere
Categories of Air Pollutants
Control of Air Pollution
Acid Deposition
Ozone Depletion
Global Warming and Climate Change
Addressing Climate Change
Indoor Air Pollution
The Atmosphere
 The atmosphere is composed of
78.1% N, 20.9% O and about 1% of
other gases such as argon, carbon
dioxide, methane, and water vapor.
 Most of the atmosphere is held close
to the Earth by the pull of gravitational
force, thus it gets less dense with
increasing distance from the Earth.
The Atmosphere
 Atmosphere is composed of 4 layers:
• The troposphere extends from the Earth’s
surface to about 10 km above the Earth.
• It actually varies from 8-18 km depending
on the position of the earth and the
seasons.
• Its T declines 6° C for every km above the
surface.
• It contains most of the water vapor and it
is where the weather takes place.
 The stratosphere extends from the top of
the troposphere to about 50 km above the
Earth.
• Most ozone is located in a band between 15
and 30 km.
• It absorbs sunlight and makes the upper layer
warmer.
 The mesosphere extends from 50-80 km
above the Earth.
 The thermosphere extends to about 300
km above the Earth.
The Atmosphere
The Atmosphere
 As the air absorbs heat from the Earth, it
expands and rises.
• When heat is radiated into space, air cools,
becomes more dense, and flows toward the
Earth.
 As the air circulates vertically, it also moves
horizontally as the Earth spins on its axis.
 The combination of all air movements creates
the wind and weather patterns characteristic
of different regions of the world.
Pollution of the Atmosphere
 Air quality is degraded by multiple sources.
 Pollution is any addition of matter or energy
that degrades the environment for humans
and other organisms.
 Because human actions are the major
cause of pollution, we can do something to
prevent it.
 Automobile emissions, chemical odors,
factory smoke, and similar materials are
considered air pollution.
 Several natural sources of gases & particles
degrade air quality:
• Volcanoes’ materials, dust from wind erosion,
gases from decomposition of dead plants and
animals are some sources.
• Pollution is directly related to # of people & their
activities in an area.
• Small population w less E use, cause less
pollution, releases diluted pollution.
• Air pollution includes both aesthetic and human
health problems.
Pollution of the Atmosphere
 Air pollution is directly related to the number
of people living in an area and the kinds of
activities in which they are involved.
 In urbanized, industrialized societies, there
are dense concentrations of people that use
large quantities of fossil fuels for
manufacturing, transportation, and domestic
purposes.
 These activities release large quantities of
polluting byproducts into our environment.
Pollution of the Atmosphere
 In urbanized areas, pollution cannot be
sufficiently diluted before the air reaches
another city.
• Polluted air from Chicago is further polluted
when it reaches Gary, Indiana;
• is supplemented by wastes of Detroit and
Cleveland,
• and finally moves over southeastern Canada
and New England to the ocean.
 Air pollution is not just an aesthetic problem; it
also causes health problems.
Pollution of the Atmosphere
The popn concentration in eastern N America creates the conditions that
lead to regional air poln problems. Since the prevailing winds are from
west to east, each city adds its pollutants, & the air quality deteriorates.
Air pollution and population centers
Pollution of the Atmosphere
Air pollution and population centers
Pollution of the Atmosphere
 Many of the megacities of the developing world
such as Beijing, Mexico City & Cairo have
extremely poor air quality, exceeding WHO air
quality for at least two pollutants.
• Air pollution increases the death rate (usually in elderly,
the infirm, & very young ones) and lowers the general
health of the population.
– Chronic coughing and susceptibility to infections are
common.
– 20-30% of respiratory diseases are caused by air pollution.
– Bronchial inflammation, allergic reactions, irritation of the
mucus of eyes & nose
Categories of Air Pollutants
 Five major types of materials are released
directly into the atmosphere in unmodified
forms in sufficient quantities to pose a health
risk. These are called primary air
pollutants.
 They are:
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Carbon monoxide
Volatile organic compounds (hydrocarbons)
Particulate matter
Sulfur dioxide
Oxides of nitrogen.
Categories of Air Pollutants
 Secondary air pollutants form under reaction of
primary pollutants and water or sunlight.
• Ozone
 Criteria air pollutants are those pollutants for
which specific air quality standards have been set
by EPA.
• Nitrogen dioxide (NO2)
• Ozone (O3)
• Sulfur dioxide (SO2)
• Particulate matter (PM)
• Carbon monoxide (CO)
• Lead (Pb)
Additionally certain compounds w high toxicity are known as
hazardous air pollutants or air toxics.
Categories of Air Pollutants
 Carbon monoxide is produced when
organic materials are burned with
insufficient oxygen.
• The single largest source is the
automobile.
–60% from vehicles driven on roads.
–20% from vehicles not used on roads.
• Not a persistent pollutant. Readily
combines w O2 forming CO2 so air can be
cleared of it.
• Increased fuel efficiency & use of catalytic
converters has reduced CO but # of
automobiles & miles driven increased it.
• Carbon monoxide binds to hemoglobin in
blood and makes the hemoglobin less able to
carry oxygen.
• It is most dangerous in enclosed spaces;
several hours of exposure to air containing
only 0.001% CO can cause death.
 Cigarette smoking is an important source
because the person is inhaling CO directly.
 U.S. levels of CO have decreased by about 67%
between 1970 and 2007.
Categories of Air Pollutants
Carbon monoxide.
Categories of Air Pollutants
 Particulate matter consists of
minute pieces of solid materials
(< 10 microns) and liquid droplets
dispersed into the atmosphere.
• The EPA has set standards for
particles smaller than 10 microns
(PM10 ) and 2.5 microns (PM 2.5).
• Larger than 2.5 microns are primary
pollutants; Travel on roads, agricultural
activities, construction sites, industrial
processes & smoke particles from fires
are their primary sources;
• smaller than 2.5 are mostly secondary
pollutants.
• Particulates can accumulate in lungs and
interfere with the ability of lungs to
exchange gases.
• They can be carcinogen.
Categories of Air Pollutants
 Droplets & solid particles can serve as
deposition site for PM.
 Breathing air containing PM, put us in contact
w potential harmful materials such as sulfuric,
nitric and carbonic acids.
 Amount of PM10 has decreased 80% between
1970 and 2004.
 U.S. EPA has been setting PM2.5 standards
for a shorter period of time.
• Amount decreased 7% between 1996 and 2002.
Categories of Air Pollutants
 Sulfur dioxide (SO2) is a compound of sulfur
and oxygen produced when sulfurcontaining fossil fuels are burned.
 It has sharp odor, irritate respiratory tissue,
aggravates asthmatic & other respiratory
conditions, reacts w water and O2 to form
sulfuric acid.
• Burning coal releases SO2.
• Today over 70% of SO2 released into the
atmosphere is from coal-burning power plants.
– U.S. levels of SO2 decreased 51%
between 1970 and 2004.
– 1306: Edward I, England, banned “sea
coles” burning, responsible for city’s poor
air quality
– 1952: London was the site of one of the
earliest killer fogs. dense fog, not mixed w
air bec of T, factories released smoke &
dust, respiratory problem, 4000 death,
bronchial irritation, soar throat, chest pain
Nearly all communities meet the SO2 standards
set by the U.S. EPA.
Categories of Air Pollutants
 Burning of fossil fuels produces a
mixture of nitrogen-containing
compounds known as oxide of nitrogen.
 The nitrogen and oxygen molecules in
the air combine with one another when
subjected to the high temperatures of
combustion.
• Nitrogen monoxide (NO) (produces primarily) and
nitrogen dioxide (NO2) (a secondary pollutant) are the
most common.
» causes respiratory problem, acid
precipitation,
» they are important in production of
secondary pollutants known as
photochemical smog.
• The automobile engine is primary source, accounting
for 38% of NOx emissions.
– Non-road motorized equipment produces 21%
– Electrical generations produces 22%
• U.S. levels decreased 30% between 1970 and 2004.
Categories of Air Pollutants
 About 75% of the NO produced by an
automobile engine is converted back into N2 and
O2 by the catalytic converter.
• An increase in the number of cars and miles driven
offsets the gains attributable to catalytic converters.
 Although all communities meet the EPA
standards for nitrogen oxides, they remain a
problem because they contribute to the
development of photochemical smog.
Categories of Air Pollutants
 Lead (Pb) can enter the body
through breathing airborne
particles or consuming lead
deposited on surfaces.
 Lead accumulates in the body
and can cause mental retardation
and kidney damage.
 Leaded gasoline was primary
source.
• Currently, about 80% of gasoline sold in
the world is unleaded.
• North American lead levels fell 94%
between 1982 and 2005.
– Paints are another major source of lead,
cause colorful pigmentation, causing
toxicity in babies chewing on painted
surfaces,
– industries such as metal smelters &
manufacturers of batteries account for
80% lead emission.
• In the U.S. lead emissions peaked at about 258,000 tons per year.
In 2007 they were about 1300 tons per year, a reduction of 99.5%,
meeting EPA standards in the U.S.
Categories of Air Pollutants
Amnt of lead released in air has declined since 1980 when
lead was removed from gasoline.
Lead emissions
Categories of Air Pollutants
 Volatile organic compounds are also known as
hydrocarbons, a group of organic compounds consisting
of carbon and hydrogen.
 VOCs found in air are either evaporated from automobile
fuel or remnants of fuel incompletely burned.
– 90% come from vehicle & industrial activities & contribute to
secondary formation
 The use of internal combustion engines accounts for 37%
of VOCs released into the air.
• Solvents contribute about 22%
• Fires contribute about 15%
 Refineries and other industries contribute an equal amount.
Categories of Air Pollutants
 Consumer products such as oil-based paint, charcoal
lighter, and other chemicals are important.
 Automobile modifications have significantly reduced
the amount of VOCs entering the atmosphere.
• Catalytic converters are used to burn exhaust gases more
completely.
– Recycling gases in engine to burned, increasing O2 in fuel-air
mix, using devices to prevent escape of gases from fuel tanks &
crankcase
– Industries are require to account for their emission & encouraged
to substitute nonvolatile for volatile organic compounds.
• U.S. levels decreased 55% between 1970 and 2004.
Categories of Air Pollutants
 VOCs aid the production of secondary air
pollutants found in smog.
 Some VOCs are toxic and are known as
hazardous air pollutants.
 The EPA does not publish VOC reduction data.
• VOC levels are reduced when ozone levels fall. VOC
levels have fallen substantially in recent years.
Categories of Air Pollutants
 Ozone (O3) is a molecule of three
oxygen atoms bonded to one another.
•It is an extremely reactive secondary
pollutant that can:
– Cause permanent lung damage
– Irritate respiratory tissues
– Damage plants, destroys chlorophyll
– Reduce agricultural yields
–
Ozone levels fell by only about 9% from 1990 to 2007 and
are still a problem particularly in southern California and
the U.S. Northeast.
Categories of Air Pollutants
 Photochemical smog is a mixture of primary
and secondary pollutants.
 It forms when primary pollutants (nitrogen
dioxide and VOCs) interact under the
influence of sunlight.
• Two most destructive components:
– Ozone
– Peroxyacetyl nitrates
Both are excellent oxidizing agents that react w
biochemical molecules & destroy them.
Categories of Air Pollutants
Development of photochemical smug begins w release of N oxides &
VOCs associated w automobile use during morning traffic. As the
sun rises & the day warms up, these reactants interact to form ozone
& other secondary pollutants. These peak during the early afternoon
& decline as the sun sets.
Daily changes in photochemical smog
Categories of Air Pollutants
 Cities with warm climates and lots of sunlight are
more prone to develop photochemical smog.
• Warm temperatures and sunlight are needed.
• Smog is more likely to be a problem in the summer
with higher temperatures and longer days.
• Cities adjacent to mountains or in valleys tend to have
trouble with photochemical smog because pollutants
are trapped by thermal inversions.
Categories of Air Pollutants
 Cities adjacent to mountains or in valleys
tend to have trouble with photochemical
smog because pollutants are trapped by
thermal inversions.
• Formation of smug needs NO, NO2, VOC,
sunlight & warm T.
• Climate, traffic, geographic features are
important
• Higher in near mountain rang or in valley
 Thermal inversions occur when warm air
becomes sandwiched between two layers of cold
air and acts like a lid on a valley.
 Warm air cannot rise, causing smog accumulation.
 To dec O3, must reduce NOx & VOC
 Requires a change in auto design or fuel
 Smog problems can be reduced by Reformulating
gasoline & installing devices on automobile
(reduces NOx & VOC), removing popn centers
away from valley
• Ozone levels fell by about 9% from 1990 to 2007 and are still a
problem, particularly in southern California and the U.S. Northeast.
• Since ozone is produced by VOCs and Nox it is necessary to further
reduce the levels of these two components to decrease the
production of ozone.
Categories of Air Pollutants
Under normal conditions, (a) the air at the earth’s surface is heated by the sun & rises to mix w
the cooler air above it. When a thermal inversion occurs (b & c) a layer of heavier cool air flows
into a valley & pushes the warmer air up. The heavy cooler air is then unable to mix w the lessdense warm air above & can’t escape bec of surrounding mountains. The cool air is trapped,
sometimes for several days, & accumulates pollutants. If the thermal inversion continues, the
levels of pollution can become dangerously high.
Thermal inversion
Categories of Air Pollutants
 Hazardous air pollutants (HAP), or air toxics, are
compounds that can harm human health or
damage the environment.
• Some released from consumer activities:
– Benzene escapes during automobile refueling.
– Some consumer products such as glues and cleaners
release toxic materials into the air.
• The majority are released from manufacturing:
– Perchloroethylene is released from dry cleaning processes
& toxic metals from smelters.
Control of Air Pollution
 Control of air pollution depends on type of pollutants &
willingness or ability of industry, government & individuals to
make changes.
 All of the air pollutants examined thus far are produced by
humans. Thus, their release into the atmosphere can be
controlled.
• In the U.S., implementation of the Clean Air Act has been the
primary means of controlling air pollution.
 Motor vehicles are the primary source of several important
air pollutants: carbon monoxide, VOCs, and nitrogen
oxides.
 Engineering changes in autos have reduced the amount of
VOCs that escape from the gas tank and crankcase.
 Modifications to the pumps at gas stations and filler pipes of
cars has been beneficial.
 Lead-free fuel has reduced the amount of lead in
the atmosphere.
 Ozone levels depend on VOC and NO2 levels,
and have fallen somewhat but still need
improvement in some areas of the country,
particularly California and the northeast U.S.
 Ozone is a secondary pollutant of automobile
use.
 Placing controls on emissions has resulted in a
significant improvement in air quality in North
America.
• U.S. regulations have pressured the
automobile industry to reduce emissions.
– Positive Crankcase Ventilation Valve (PCV)
– Air Pollution Control Valves (APC)
– Catalytic Converters
– Lead-Free Fuel
NOX levels have not significantly decreased
because people are driving more kilometers per
year.
Control of Pollution
 In the U.S., implementation of the requirements
of the Clean Air Act has been the primary means
of controlling air pollution.
• Under the Clean Air Act, a variety of pollution control
mechanisms have been employed and the quality of
air has improved significantly in the last 27 years.
• The EPA is responsible for developing and meeting
air quality standards.
• Industry must meet a series of detailed control
requirements with the goal of improving air quality.
Control of Air Pollution
Improvement in air quality
Control of Air Pollution
 Particulate Matter Emissions
• Industrial activities produce dust
– Mining, farming operation, transfer of grain or coal all
produce dust and are sources of particulate emissions.
• Improper land use is a major source of airborne
particles.
– Overgrazing
• Fossil fuel burning is another major source of particulate
matter.
– Diesel engines are a significant source of particulate matter.
• Personal activities
– Forest fires, grass fires, leaf burning, fireplaces, and
woodstoves are a significant source of particulate matter
Fireplaces and wood-burning stoves
–Some cities enforce a ban on wood
burning fireplace during severe air
pollution episodes
–Some alert people not to use them
–Some regulate # & efficiency of wood
burning devices
–Some prohibit construction of houses w
fire place & wood burning stoves
Control of Air Pollution
 Power Plant Emissions: primary source of SO2 is
electric power generating plants
• Several possibilities exist for controlling sulfur dioxide:
– Switch to low-sulfur fuel can dec it by 66%, switching to oil,
natural gas, or nuclear fuels reduce it even more
– Remove sulfur from fuel by physical/chemical treatment
before use dec it by 40%, but inc the cost of electricity.
– Scrubbing gases emitted from smokestack. They are costly to
install, maintain & operate which passes the cost to the
consumers. Filters and mechanical means control particulates.
• The control of sulfur dioxide requires changes to the way electricity is
produced. The EPA has set limits and allow the electric utility to decide
which options are best for them.
Control of Air Pollution
 The Clean Air Act provides the principal
framework for national, state, tribal, and
local efforts to protect air quality.
 Under the Clean Air Act, emissions of the six
worst air pollutants dropped 54% from 1970
to 2004, despite an increase in energy
consumption of 42%.
 EPA estimates the Clean Air Act’s human
health, welfare, and environmental benefits
have outweighed costs 40 to 1.
Control of Air Pollution
 Low-sulfur coal reduces sulfur emissions by
66%.
 Switching to oil, natural gas, or nuclear fuels
further reduces sulfur emissions.
 40% of sulfur can be removed before the fuel is
used.
 Smokestack gases can be scrubbed before they
are emitted.
• The technology is available, but costly to install,
maintain, and operate.
Series of detailed control requirements the federal
government implements and states administer.
• Conduct periodic reviews for six principal pollutants
• Ensuring air quality standards are met
• Reduce emissions of SO2 & NOx that cause acid rain
• Reduce air pollutants such as PM, SOx, NOx, that
reduce visibility across large regional areas
• Ensure sources of toxic air pollutants causing cancer
& adverse human health & env risks are well
controlled
• Limit use of chemicals that damage the stratospheric
ozone layer
Air Quality Act was initially enacted in 1967, later
was amended in 1970, 1977, 1990
 Required industry to obtain permits to release
material in air
 New & existing sources of pollutions are subject to
national & ambient air quality standards
 New sources were under more stringent control
 Hazardous air emission were regulated
 Allow sell of SO2 release permit by power plants
 Program to phase out O3 depleting substances
– Emissions of six worst air pollutants dropped 54% from
1970 to 2004, despite an increase in energy consumption
of 42%.
– EPA estimates envl benefits have outweighed its costs by
40 to 1.
Acid Deposition
 Acid deposition is the accumulation
of potential acid-forming particles on
a surface.
 When dry particles are deposited, an
acid does not actually form until these
materials mix with water.
 All of these sources of acid-forming
particles are commonly referred to as
acid rain.
• Sulfur Dioxide and Nitrogen oxides are
carried aloft by wind and form secondary
pollutants (acids), and then are carried
back to earth in wet (snow, rain, fog) and
dry (particulate) forms.
• Acids results from natural causes such as
vegetation, volcanoes, lightning, & from
human activities such as burning of coal, &
use of combustion engine.
• In 1969 New Hampshire had a rain w a pH
of 2.1 & in 1974 in Scotland one w pH of
2.4
Acid Deposition
Molecules from natural sources, power plants, & internal combustion
engines react to produce chemicals that are sources of acid deposition.
Sources of acid deposition
Acid Deposition
 Acid rain is a worldwide problem.
 Acid rains can have concentrations of acid 1000
times higher than normal.
 Harmful effects of acid rain include:
• Property and structural damage
– Limestone degradation: limestone is a common material
for building & is relatively soft.
• H2SO4 a major component of acid rain, converts
limestone to gypsum which is more soluble & is
eroded over many years of contact w acid rain.
• Effect of acid rain on ecosystem is
subtle & difficult to quantify but is
suspected of causing death of many
forests & has decreased rate of growth
of others.
• Damage to forests
–Acidic soil results in reduced nutrient
absorption
• Lake acidification causes food chain
disruption
 Foliage Damage:
• in areas that soil can’t buffer the additional
acid, Al is released from binding sites &
become part of the soil & water & interfere
w ability of the plant roots to absorb
nutrients.
• Acidic Soil - Reduces Nutrient Absorption;
inc Al dec Ca, Mg.
• Reduction of pH may change kinds of
bacteria in soil & reduce availability of
nutrients.
 Weakened Plant Defenses
• Stressors: all these factors together inc stress on the plant &
may allow other factors such as insect infestation to further
weaken tree & cause its death.
 Lake Acidification: cause progressive lost of many kinds of
organism,
• Food Chain Disruption: many organisms fail to reproduce,
may be due to sensitivity of early developmental stages to
these changes, or due to the fact that many young ones live
in shallow water w more acid content,
• A big concern specially during spring snowmelt which
releases large amnt of acid.
• Inc pH reduces ability of crayfish & other crustaceans to form
new exoskeletons so they die.
• Reduced Ca availability also results in the development of
some fish w malformed skeletons.
Control of Air Pollution
 The two most problematic air pollution
problems are ground-level ozone and
particulate matter.
 In 2005, 15 U.S. cities had unhealthy levels
of ground-level ozone for 30 or more days.
 To reduce these two pollutants, it is
necessary to decrease pollution from power
plants and motor vehicles.
 New legislation or more stringent regulations
will be required for that to occur.
Ozone Depletion
 In 1970’s a decreased in O3 layer
became a big concern.
 Ozone is formed in the stratosphere
when high energy ultraviolet radiation
splits diatomic oxygen into atomic
oxygen.
• The atomic oxygen may then combine
with another diatomic oxygen molecule
to form triatomic oxygen (Ozone - O3).
 In 1985, it was discovered that a
significant thinning of the ozone layer over
the Antarctic occurred during the
Southern Hemisphere spring.
 This area became known as the “ozone
hole.”
 Ozone in the outer layers of the
atmosphere shields the Earth from the
harmful effects of ultraviolet light radiation
which can cause inc in skin cancer,
cataracts & mutation incidents.
Ozone Depletion
 Chlorofluorocarbons (CFC) are strongly
implicated in the ozone reduction in the upper
atmosphere.
 It can take 10 to 20 years for chlorofluorocarbon
molecules to get into the stratosphere.
 They can then react with the ozone for up to 120
years.
 In the stratosphere, UV radiation breaks down
CFC molecules, releasing atomic chlorine.
 A free chlorine atom reacts with an ozone
molecule, converting it from O3 to O2.
Ozone Depletion
 In 1987, several industrialized countries
including Canada, the United States, the
United Kingdom, Sweden, Norway,
Netherlands, the Soviet Union, and West
Germany agreed to freeze chlorofluorocarbon
production and reduce production by 50% by
2000.
 This document, known as the Montreal
Protocol, was ratified by Congress in 1988.
 As a result, emissions dropped 87% from their
peak in 1988.
– In 1990 in London, international
agreements were reached to further
reduce the use of CFCs.
– Lack of funds from developed
countries to help less-developed
countries to obtain technology to
obtain refrigerators & air conditioners
w/o CFCs was an obstacle.
– In 1991 DuPont announce the
development of new refrigerators that
will not harm O3 layer
Global Warming and Climate Change
 Recently scientists noticed an inc in T of the Earth &
tried to find out if it is a natural process or is the result of
human activities.
 CO2, CH4, CFC, NO are known as greenhouse gases.
 Their accumulation causes the sunlight to enter
atmosphere but causes slow lost form Earth surface.
 Climatic records indicate over the past 160,000 years a close
correlation between greenhouse gas concentration and
global temperatures.
 UN established the Intergovernmental Panel on Climate
Change (IPCC) to study the issue & make
recommendations.
Global Warming and Climate Change
 A main activity of IPCC is to provide on
regular intervals an assessment of the state of
knowledge about climate change.
 IPCC Conclusions
• 1996 Assessment - Concluded climate change is
occurring and it is highly probable human activity
is importance cause of the change.
• Average temperature of the earth increased 0.5 to
1.0 degrees Fahrenheit over the last 100 years.
• Strong correlation between temperature increase
and amount of greenhouse gases in the
atmosphere.
• Human activity greatly increases amounts of
greenhouse gases in atmosphere.
Global Warming and Climate Change
 The Third Assessment Report, Climate
Change 2001, concluded:
• The average temperature on Earth has increased
0.3 to 0.6°C (0.5-1.0° F) in the past 100 years.
During that same period, sea level has risen 4-10
inches. 1998 was the hottest year on record; 2005
was the second warmest; 2002 was the third.
• A strong correlation exists between temperature
increase and amount of greenhouse gases in the
atmosphere.
• Human activity greatly increases amounts of
greenhouse gases in atmosphere.
Global Warming and Climate Change
 The Fourth Assessment Report, Climate Change
2007, concluded:
• The average temperature on Earth has increased 0.56 to
0.92°C (1.0-1.7° F) in the past 100 years. 1998 was the
hottest year on record; 2005 was the second warmest;
2002 was the third.
• Sea level is rising about 1.8 mm/yr or 18 cm in 100 years.
• A strong correlation exists between temperature increase
and amount of greenhouse gases in the atmosphere.
• Human activity greatly increases amounts of greenhouse
gases in atmosphere.
Global Warming and Climate Change
What causes global warming?
 Several gases in the atmosphere are
transparent to UV & visible light but absorb
infrared radiation & allow sunlight to penetrate
the atmosphere.
 Greenhouse effect:
• Greenhouse gases allow sunlight to penetrate the
atmosphere.
• Sunlight is absorbed by Earth’s surface.
• It is reradiated as infrared energy (heat).
• The heat is absorbed by gases in the atmosphere.
Global Warming and Climate Change
Greenhouse effect naturally warms Earth’s surface. w/o it Earth would
be 33° C=66° F cooler than today which will be inhabitable for life as
know it.
Greenhouse effect
Global Warming and Climate Change
 Carbon dioxide is the most abundant of the
greenhouse gases.
• Deforestation contributes to the amount of carbon
dioxide in the atmosphere. Fossil fuel burning, 19%
inc from 1958 to 2003.
 Methane comes from biological sources and
from some fossil-fuel burning activities.
• Breakdown of organic material by anaerobic bacteria.
• Particularly abundant in wetlands & rice field, it also
exist in guts of termites & various kinds of ruminant
animals such as cattle.
 Nitrous oxide enters the atmosphere from
fossil fuels and fertilizers. a minor
component of the greenhouse gas picture,
• Biomass burning, Breakdown of nitrogen-rich
products, Fossil fuels & fertilizers are main
sources.
 Chlorofluorocarbons from refrigerants,
cleaning solvents, and propellants are also
a component of the greenhouse effect.
• Entirely human activities.
• Even in minor amnt, extremely efficient as
greenhouse gas.
Potential Consequences of Global Warming
 Even small inc in T sets in motion changes that could
significantly alter the climate of major regions of the world.
• Computer models suggest a cascade of consequences that affect the
hydrologic cycle, sea level, human health, the survival and distribution of
organisms, and the use of natural resources by people.
 It can inc incidents of severe weather & change rain fall pattern.
 Magnitude & rate of change will differ from region to region.
 Some natural ecosystems or human settlements will be able to
withstand or adopt, others not.
 Poorer nations more vulnerable bec of more dependent on
climate-sensitive sectors such as subsistence agriculture.
 Africa is considered the most vulnerable continent.
Global Warming and Climate Change
 Potential Consequences of Global
Warming
• Rising Sea Level
–Beach and coastal wetland erosion.
–Substantial loss of coastal area.
–Land area of some island nations and
countries like Bangladesh would change
dramatically as flooding occurred.
Global Warming and Climate Change
 Potential Consequences of Global Warming
 Rising Sea Level
• Water expands when it is warmed.
• Melting glaciers add more water to the oceans.
– Beaches and coastal wetlands erode, inundating lowlying areas, and coastal areas become more vulnerable
to flooding from storm surges and intense rainfall.
– By 2100 sea level is expected to rise 15–90 cm or
6–35 inches.
– A 50 cm rise results in substantial land loss in North
America.
Global Warming and Climate Change
 Potential Consequences of Global
Warming
• Disruption of Water Cycle
– Droughts in some areas, flooding in others.
– Navigation
– Hydropower
– Water quality, supply, and demand
– Flood control
– Environmental quality and recreation
– Political issues
• Navigation: by affecting water level &
flooding/drought frequency
• Hydropower: depend on water flow
• Water Supply and Demand: by affecting runoff &
water level in rivers, lakes, aquifers
• Flood Control: by changing frequency & severity
of inland flooding
• Environmental Quality and Recreation
Political Issues: inc tension among countries that
depend on water supplies from outside their
borders
Global Warming and Climate Change
 Health Effects
–Most direct effect of climate change
would be impacts of hotter
temperatures.
–Hot temperatures force cardiovascular
system to work harder to cool the
body.
–Heat exhaustion and some respiratory
problems increase.
–Aggravate air quality problems. Inc in T
increases O3 level at ground level.
–Ozone will injure lung tissue & intensifies
effects of airborne pollen & spores.
–Spread of tropical disease such as malaria,
dengue fever, yellow fever, and
encephalitis to temperate parts of the
world.
Global Warming and Climate Change
• Changing forests
– Geographic distributions of vegetation.
– Accelerated loss of species.
• Equatorial organisms move toward the poles, and tundra biomes are
affected due to the thawing of permafrost.
• Coral reefs are affected by increased water temperature and
increased acidity of ocean water from dissolved CO2.
• Low lying islands and shorelines are impacted by rising sea level.
Mangrove forests and marshes will be inundated and subjected to
violent weather and storm surges.
• Challenges to agriculture
– Increased CO2 concentration likely to increase crop
yields in some areas and decrease yields in other
areas.
 In regions with drought and heat stress, yields will fall.
 Yields will increase in areas with warmer temperatures
and more rainfall.
 Episodes of severe weather will cause crop damage that
will affect yields.
• Dec flexibility in crop distribution & inc
irrigation demand.
• Pest range expansion could increase
vulnerability & inc use of pesticides.
 Unanticipated Changes
• Greatest risks may be those yet to be
discovered, Such as more frequent or
severe hurricanes, shift in ocean currents,
& moderation of climate in N Europe.
Global Warming and Climate Change
Global warming have several effects on climate of world which
would have great impact on human & other living things.
Effects of global warming
Global Warming and Climate Change
Addressing Climate Change
 Approaches to dealing with climate change involve
technological change coupled with political will and
economic realities.
• Increase efficiency of energy utilization and reduce
carbon dioxide production.
– Carbon Tax on amnt of C individuals & industry
release will inc cost of fuel & stimulate search for
alternative fuel
• Increase the amount of carbon dioxide removed from
the atmosphere.
– Increased vegetation growth.
– May be a short-term benefit.
–Increased vegetation growth will Inc
photosynthesis
–Some argue this is only a Short-term
benefit since trees will die & their
decay release CO2,
–Tropical regions are very important in
removing CO2 & storing it in plant
structure.
–Burning of tropical rainforest for
agricultural & grazing purposes adds
to CO2 in atmosphere & reduces their
ability to remove CO2 efficiently.
Addressing Climate Change
 Political and Economic Forces
• It will be more difficult to achieve global
consensus to reduce CO2 emissions, as CO2 is
released as a result of energy consumption
which affects all sections of the economy.
• Increases in energy efficiency and reductions in
greenhouse gas emissions are likely to have
important related benefits that could offset the
costs.
– Improving fuel efficiency and reducing pollution
can be offset by lower health care costs and higher
worker productivity.
–Many cost-effective technologies (inc E
efficiency in buildings) could cause sizable
dec in greenhouse gas emission,
–Inc fuel efficiency will dec pollution & dec
health care cost which will inc productivity,
reduces the need for new power plans &
related infrastructure,
–Wind E system, conversion of sunlight to
electricity are some candidates for longerterm technological transition
Addressing Climate Change
–Many candidates for longer-term
technological transition have
been identified, and some have
already begun to penetrate the
market.
–Wind energy systems competitive
with coal-burning power plants.
Addressing Climate Change
– The U.S. DOE has concluded that relying on
already proven technology, the U.S. could
reduce its carbon emissions by 400 million
metric tons in 2010.
– This would stabilize emissions in that year at 1990
levels
– Savings from reduced energy costs would be roughly
equal to the added cost of investment.
– Resources and policies to increase investment
in renewables and other long-term technologies
will be needed.
Indoor Air Pollution
 Growing evidence indicates air within homes
and other buildings can be more seriously
polluted than outdoor air in the most
industrialized cities.
 These pollutants are thought to have adverse
effects on human health.
• Asbestos
• Formaldehyde (in many consumer products)
• Airborne pesticide residues
• Chloroform
• Perchloroethylene
• Paradichlorobenzene
Indoor Air Pollution
 Smoking is the most important pollutant.
 Weatherizing to increase efficiency slows air
exchange and tends to trap pollutants.
 Average person spends almost 90% of time
indoors.
 Movements to reduce indoor air pollution lag
behind regulations governing outdoor air
pollution.
 The EPA is conducting research to identify and
rank the human health risks that result form
exposure to individual indoor pollutants or
mixtures of multiple indoor pollutants.
Indoor Air Pollution
 Secondhand smoke is exposure to
environmental tobacco smoke as a result of
living and working in places where people
smoke.
 In July 1993, the EPA recommended several
actions to prevent people from being exposed to
secondhand indoor smoke:
• People not smoke in their homes or permit others to
do so
• All organizations that deal with children have policies
that protect children from secondhand smoke.
Indoor Air Pollution
• Every company have a policy that protects
employees from secondhand smoke
• Smoking areas in restaurants and bars be placed
so that the smoke will have little chance of
coming into contact with nonsmokers.
• Today only 16 states do not have some kind of a
statewide ban on smoking in public places.
• Even if a state does not have legislation, many
cities and other jurisdictions within those states
do.
Indoor Air Pollution
 Radon is an inert radioactive gas with a half-life of 3.8 days.
 It is formed as a byproduct of uranium-238 decay before
becomes stable, nonradioactive, lead 206.
 An inert gas that does not enter into any chemical
reactions w/in the body.
 Increased incidence of lung cancer is the only known health
effect associated with radon decay products.
 Goes under radioactive decay to produce “daughters” of
radon in human lungs when inhaled.
 “Daughters” of radon stay in the lungs & are chemically
active
Indoor Air Pollution
 Radon usually diffuses up through rocks and soil
and escapes harmlessly into the atmosphere, but it
can diffuse into groundwater.
 It can enter a home through an open space in the
foundation, from gaps around pipes, or from wells.
 The EPA and the U. S. surgeon general
recommend that all Americans (with a few
exceptions) test their homes for radon.
 If radon is detected, simple and inexpensive
actions may be taken to lower the level in the
home.
Indoor Air Pollution
Generalized geologic radon potential of the United States
Indoor Air Pollution
 Noise is unwanted sound.
 Research has shown that exposure to noise can
cause physical as well as mental harm.
 The loudness of a sound is measured by decibels.
 The frequency or pitch of a sound is a factor in
determining its degree of harm.
 Noise pollution is linked to a variety of ailments;
research has also shown it may also cause blood
vessels to constrict, it disturbs unborn children,
and sometimes causes seizures in epileptics.
 Prolonged exposure to sounds of about 80 to 85
decibels (a measure of the intensity of a sound wave)
can cause permanent hearing loss.
 Two common sources of noise at this level or higher
• the workplace,
• large gatherings of people at sporting events, and rock
concerts.
 The Occupational Safety and Health Administrations
(OSHA) has set standards for the workplace, but
there are no such standards for rock concerts, which
can be much louder than most workplaces.
 Most hearing loss occurs during the first 2 hours of
exposure, but hearing recovers within 2 hours after
the exposure stops.
 Those continually exposed, however, can suffer
permanent impairment.
 Other complications of noise are: tinnitus, a constant
ringing or buzzing in the ears, causing seizures in
epileptics.
 The Noise Control Act of 1972 was the first major
attempt in U.S to protect the public health & welfare
from detrimental noise.
Indoor Air Pollution
 Many European countries do more to
control noise than the U.S. does.
• Several European countries have developed
quiet construction equipment in conjunction
with strongly enforced noise ordinances.
Summary
 The atmosphere has a tremendous ability to
disperse pollutants.
 Carbon monoxide, hydrocarbons, particulate
matter, sulfur dioxide, and oxides of nitrogen are
the primary air pollutants.
 The U.S. EPA establishes standards for six
pollutants known as criteria air pollutants: carbon
monoxide, nitrogen dioxide, sulfur dioxide, volatile
organic compounds, ozone, and lead.
 Acid rain is caused by emissions of sulfur dioxide
and oxides of nitrogen in the upper atmosphere.
Summary
 These compounds form acids that are washed
from the air when it rains or snows or settle as
particles on surfaces.
 The control of acid rain requires the use of
scrubbers, precipitators, and filters, or the
removal of sulfur from fuels.
 Many are concerned about the damaging effects
of greenhouse gases: carbon dioxide, methane,
and chlorofluorocarbons.
Summary
 These greenhouse gases are likely to be
causing an increase in the average temperature
of the Earth and are leading to major changes in
the climate.
 Significant impacts on our health, the vitality of
forests and other natural areas, the distribution
of freshwater supplies, and the productivity of
agriculture are among the probable
consequences of climate change.
Summary
 Chlorofluorocarbons also lead to the destruction
of ozone in the upper atmosphere, which results
in increased amounts of ultraviolet light reaching
Earth.
 Many commonly used materials release gases
into closed spaces (indoor air pollution) where
they cause health problems.
 The most important of these health problems are
associated with tobacco smoking.