Human Impact on the
Atmosphere
Chapters 18 and 19
Living in the Environment, 11th Edition, Miller
Advanced Placement Environmental Science
La Canada High School
Dr. E
Pollution
Thorpe, Gary S., M.S., (2002). Barron’s How to prepare for the AP Environmental Science Advanced Placement Exam
• The term “Smog” (smoke and fog) was first
used in 1905 to describe sulfur dioxide
emission
• In 1952, severe pollution took the lives of
5000 people in London
• “It isn’t pollution that’s harming the
environment. It’s the impurities in our air and
water that are doing it.”
Former U.S. Vice President Dan Quayle
www.aqmd.gov/pubinfo/ 97annual.html
Congress found:
• Most people now live in urban areas
The
Clean
Air
Act
• Growth results in air pollution
• Air pollution endangers living things
It decided:
• Prevention and control at the source was
appropriate
• Such efforts are the responsibility of states
and local authorities
• Federal funds and leadership are essential
for the development of effective
programs
Clean Air Act
• Originally signed 1963
– States controlled standards
• 1970 – Uniform Standards by
Federal Govt.
– Criteria Pollutants
• Primary – Human health risk
• Secondary – Protect materials, crops,
climate, visibility, personal comfort
Clean Air Act
• 1990 version
– Acid rain, urban smog, toxic air pollutants, ozone
depletion, marketing pollution rights, VOC’s
• 1997 version
–
–
–
–
Reduced ambient ozone levels
Cost $15 billion/year -> save 15,000 lives
Reduce bronchitis cases by 60,000 per year
Reduce hospital respiratory admission 9000/year
Clean Air Act
President George W. Bush signed rules
amending Clean Air Act that allowed power
plants and other industries to increase
pollution significantly without adopting
control measures
http://www.cnn.com/2003/LAW/12/24/bush.clean.air.ap/index.html
Appeals court blocks
Bush clean air changes
Wednesday, December 24, 2003 Posted: 2:10 PM EST (1910 GMT)
WASHINGTON (AP) -- A
federal appeals court on
Wednesday blocked new
Bush administration
changes to the Clean Air
Act from going into effect
the next day, in a
challenge from state
attorneys general and
cities that argued they
would harm the
environment and public
health.
Clean Air Act
http://www.epa.gov/air/oaq_caa.html
• Title I - Air Pollution Prevention and Control
– Part A - Air Quality and Emission Limitations
– Part B - Ozone Protection (replaced by Title VI)
– Part C - Prevention of Significant Deterioration of Air Quality
– Part D - Plan Requirements for Nonattainment Areas
• Title II - Emission Standards for Moving Sources
– Part A - Motor Vehicle Emission and Fuel Standards
– Part B - Aircraft Emission Standards
– Part C - Clean Fuel Vehicles
• Title III - General
• Title IV - Acid Deposition Control
• Title V - Permits
Outdoor Air Pollution
Primary Pollutants
CO CO2
SO2 NO NO2
Secondary Pollutants
SO3
Most hydrocarbons
Most suspended
particles
Natural
Sources
Mobile
HNO3
H 2 O2
H2SO4
O3
PANs
–
Most NO3 and SO24 – salts
Stationary
Major Sources of Primary Pollutants
Stationary Sources
• Combustion of fuels for power and heat – Power Plants
• Other burning such as Wood & crop burning or forest
fires
• Industrial/ commercial processes
• Solvents and aerosols
Mobile Sources
• Highway: cars, trucks, buses and motorcycles
• Off-highway: aircraft, boats, locomotives, farm
equipment, RVs, construction machinery, and lawn
mowers
54 million metric
tons from mobile
sources in 1990
Human Impact on Atmosphere
• Burning Fossil Fuels  Adds CO2 and O3 to troposphere
 Global Warming
 Altering Climates
 Produces Acid Rain
• Using Nitrogen
 Releases NO, NO2, N2O, and NH3
fertilizers and
into troposphere
burning fossil fuels
 Produces acid rain
• Refining petroleum  Releases SO2 into troposphere
and burning fossil
fuels
 Releases toxic heavy metals (Pb,
• Manufacturing
Cd, and As) into troposphere
www.dr4.cnrs.fr/gif-2000/ air/products.html
Criteria Air Pollutants
EPA uses six "criteria pollutants" as indicators of
air quality
1.
2.
3.
4.
5.
6.
•
Nitrogen Dioxide: NO2
Ozone: ground level O3
Carbon monoxide: CO
Lead: Pb
Particulate Matter: PM10 (PM 2.5)
Sulfur Dioxide: SO2
Volatile Organic Compounds: (VOCs)
EPA established for each concentrations above
which adverse effects on health may occur
Nitrogen Dioxide (NO2)
• Properties: reddish brown gas, formed as
fuel burnt in car, strong oxidizing agent,
forms Nitric acid in air
• Effects: acid rain, lung and heart
problems, decreased visibility (yellow
haze), suppresses plant growth
• Sources: fossil fuels combustion, power
plants, forest fires, volcanoes, bacteria in
soil
• Class: Nitrogen oxides (NOx)
• EPA Standard: 0.053 ppm
Mobile Source Emissions:
Nitrogen Oxides
Ozone (O3)
• Properties: colorless, unpleasant odor,
major part of photochemical smog
• Effects: lung irritant, damages plants,
rubber, fabric, eyes, 0.1 ppm can lower
PSN by 50%,
• Sources: Created by sunlight acting on
NOx and VOC , photocopiers, cars,
industry, gas vapors, chemical solvents,
incomplete fuel combustion products
• Class: photochemical oxidants
Ozone (O3)
• 10,000 to 15,000 people in US admitted
to hospitals each year due to ozonerelated illness
• Children more susceptible
– Airways narrower
– More time spent outdoors
Mobile Source Emissions:
Hydrocarbons –
Precursors to Ozone
Carbon Monoxide (CO)
• Properties: colorless, odorless, heavier than
air, 0.0036% of atmosphere
• Effects: binds tighter to Hb than O2, mental
functions and visual acuity, even at low levels
• Sources: incomplete combustion of fossil fuels
60 - 95% from auto exhaust
• Class: carbon oxides (CO2, CO)
• EPA Standard: 9 ppm
• 5.5 billion tons enter atmosphere/year
Mobile Source
Emissions - CO
Lead (Pb)
• Properties: grayish metal
• Effects: accumulates in tissue; affects
kidneys, liver and nervous system
(children most susceptible); mental
retardation; possible carcinogen; 20% of
inner city kids have [high]
• Sources: particulates, smelters, batteries
• Class: toxic or heavy metals
• EPA Standard: 1.5 ug/m3
• 2 million tons enter atmosphere/year
Suspended Particulate Matter (PM10)
•Properties: particles suspended in air (<10
um)
•Effects: lung damage, mutagenic,
carcinogenic, teratogenic
•Sources: burning coal or diesel,
volcanoes, factories, unpaved roads,
plowing, lint, pollen, spores, burning
fields
•Class: SPM: dust, soot, asbestos, lead,
PCBs, dioxins, pesticides
•EPA Standard: 50 ug/m3 (annual mean)
Mobile Source Emissions: Fine
Particulate Matter (PM2.5)
Sulfur Dioxide (SO2)
• Properties: colorless gas with irritating odor
• Effects: produces acid rain (H2SO4),
breathing difficulties, eutrophication due to
sulfate formation, lichen and moss are
indicators
• Sources: burning high sulfur coal or oil,
smelting or metals, paper manufacture
• Class: sulfur oxides
• EPA Standard: 0.3 ppm (annual mean)
• Combines with water and NH4 to increase
soil fertility
VOCs (Volatile Organic Compounds)
• Properties: organic compounds (hydrocarbons) that
evaporate easily, usually aromatic
• Effects: eye and respiratory irritants; carcinogenic;
liver, CNS, or kidney damage; damages plants; lowered
visibility due to brown haze; global warming
• Sources: vehicles (largest source), evaporation of
solvents or fossil fuels, aerosols, paint thinners, dry
cleaning
• Class: HAPs (Hazardous Air Pollutants)
– Methane
– Benzene
– Chlorofluorocarbons (CFCs), etc.
• Concentrations indoors up to 1000x outdoors
•
•
•
•
•
•
•
•
•
Other Air Pollutants
Carbon dioxide
ChloroFluoroCarbons
Formaldehyde
Benzene
Asbestos
Manganese
Dioxins
Cadmium
Others not yet fully characterized
Formation & Intensity
Factors
• Local climate (inversions, air pressure, temperature,
humidity)
• Topography (hills and mountains)
• Population density
• Amount of industry
• Fuels used by population and industry for heating,
manufacturing, transportation, power
• Weather: rain, snow,wind
• Buildings (slow wind speed)
• Mass transit used
• Economics
Thermal Inversion
cool air
Pollutants
cool air
warm air (inversion layer)
warm
air
• surface heated by sun
• warm air rises (incl. pollutants)
• cools off, mixes with air of equal
density & disperses
• surface cools rapidly (night)
• a layer of warm air overlays surface
• polluted surface air rises but cannot
disperse remains trapped
Smog Forms
...when polluted air is stagnant
(weather conditions, geographic location)
Los Angeles, CA
Primary Pollutants
CO CO2
SO2 NO NO2
Most hydrocarbons
Most suspended
particles
Natural
Sources
Mobile
Secondary Pollutants
SO3
HNO3
H 2 O2
H2SO4
O3
PANs
–
Most NO3 and SO24 – salts
Stationary
Photochemical Smog
UV radiation
Primary Pollutants
Secondary Pollutants
NO2 + Hydrocarbons
HNO3
O3
nitric acid ozone
H2O + O2
Auto Emissions
Photochemical Smog
Solar
radiation
Photochemical Smog
Ultraviolet radiation
NO
Nitric oxide
NO2
Nitrogen
dioxide
H2O
Water
O
Atomic
oxygen
O2
Molecular
oxygen
Hydrocarbons
PANs
Peroxyacyl
nitrates
HNO3
Nitric acid
Aldehydes
(e.g., formaldehyde)
O3
Ozone
Photochemical Smog
Indoor Air Pollution
Why is indoor air quality
important?
• 70 to 90% of time spent indoors, mostly at home
• Many significant pollution sources in the home (e.g.
gas cookers, paints and glues)
• Personal exposure to many common pollutants is
driven by indoor exposure
• Especially important for susceptible groups – e.g. the
sick, old and very young
Exposure
• Time spent in various environments in US
and less-developed countries
House of Commons Select Committee
Enquiry on Indoor Air Pollution (1991)
• “[There is] evidence that 3 million people have asthma in
the UK… and this is increasing by 5% per annum.”
• “Overall there appears to be a worryingly large number
of health problems which could be connected with indoor
pollution and which affect very large numbers of the
population.”
• [The Committee recommends that the Government]
“develop guidelines and codes of practice for indoor air
quality in buildings which specifically identify exposure
limits for an extended list of pollutants…”
Sources of Indoor Air Pollutants
• Building materials
• Furniture
• Furnishings and fabrics
• Glues
• Cleaning products
• Other consumer products
• Combustion appliances (cookers and heaters)
• Open fires
• Tobacco smoking
• Cooking
• House dust mites, bacteria and moulds
• Outdoor air
Important Indoor Air pollutants
• Nitrogen dioxide
• Carbon monoxide
• Formaldehyde
• Volatile Organic Compounds (VOCs)
• House dust mites (and other allergens, e.g. from pets)
• Environmental tobacco smoke
• Fine particles
• Chlorinated organic compounds (e.g. pesticides)
• Asbestos and man-made mineral fibres
• Radon
Health Effects
Nitrogen dioxide
• Respiratory irritant
• Elevated risk of respiratory illness in children,
perhaps resulting from increased susceptibility to
respiratory infection; inconsistent evidence for
effects in adults
• Concentrations in kitchens can readily exceed WHO
and EPA standards
Health Effects
Carbon monoxide
• An asphyxiant and toxicant
• Hazard of acute intoxication, mostly from
malfunctioning fuel-burning appliances and
inadequate or blocked flues
• Possibility of chronic effects of long-term
exposure to non- lethal concentrations,
particularly amongst susceptible groups
Health Effects
Formaldehyde
• Sensory and respiratory irritant and sensitizer
• Possible increased risk of asthma and chronic
bronchitis in children at higher exposure levels
• Individual differences in sensory and other
transient responses
• Caution over rising indoor concentrations
Health Effects
Volatile Organic Compounds (VOCs)
• Occur in complex and variable mixtures
• Main health effects relate to comfort and wellbeing, but benzene (and other VOCs) are
carcinogenic
• Concern about possible role of VOCs in the
aetiology of multiple chemical sensitivity; also
implicated in sick building syndrome
Health Effects
House dust mites
• House dust mites produce Der p1 allergen, a potent
sensitizer
• Good evidence of increased risk of sensitization with
increasing allergen exposure, but this does not
necessarily lead to asthma
• Small reductions in exposure will not necessarily lead to
reduced incidence and/or symptoms
• Indoor humidity is important
Health Effects
Fungi and bacteria
• Dampness and mould-growth linked to selfreported respiratory conditions, but little
convincing evidence for association between
measured airborne fungi and respiratory
disease
• Insufficient data to relate exposure to (nonpathogenic) bacteria to health effects in the
indoor environment
Health Effects
Environmental tobacco smoke (ETS)
•
•
•
•
Sudden infant death syndrome
Lower respiratory tract illness
Middle ear disease
Asthma
12 million children exposed to secondhand
smoke in homes
Health Effects
Fine particles
• Consistent evidence that exposure to small
airborne particles (e.g. PM10) in ambient air
can impact on human health; mechanisms
uncertain
• Chronic Obstructive Pulmonary Disease and
Cardiovascular Disease patients and asthmatics
probably at extra risk
• Relative importance of indoor sources is
unknown
Health Effects
Radon
• Can cause lung cancer
• Estimated that 7,000 to 30,000 Americans die
each year from radon-induced lung cancer
• Only smoking causes more lung cancer deaths
• Smokers more at risk than non-smokers
Radon Risk: Non-Smoker
Radon Level If 1000 people who did not smoke were This risk of cancer from
(pCI/L)
exposed to this level over a lifetime.. radon exposure compares
About X would get lung cancer
to …
Being killed in a violent
crime
What to do:
20
8
10
4
Fix your home
8
3
10x risk of dying in a plane Fix your home
crash
4
2
2
<1
Risk of dying in a home Fix your home
fire
1.3
<1
Average indoor radon level Fix your home
0.4
<1
Average indoor radon level Fix your home
Risk of drowning
Fix your home
Fix your home
If you are a former smoker, your risk may be higher
Radon Risk: Smoker
Radon Level
(pCI/L)
If 1000 people who smoke were
exposed to this level over a lifetime..
About X would get lung cancer
This risk of cancer from
What to do:
radon exposure compares Stop smoking and
to …
…
20
135
100x risk of drowning
10
71
100x risk of dying in a
home fire
8
57
4
29
2
15
2x the risk of dying in a car Fix your home
crash
1.3
9
Average indoor radon level Fix your home
0.4
3
Average indoor radon level Fix your home
Fix your home
Fix your home
Fix your home
100x risk of dying in a
plane crash
Fix your home
If you are a former smoker, your risk may be lower
Radon
• 55% of our exposure to radiation comes
from radon
• colorless, tasteless, odorless gas
• formed from the decay of uranium
• found in nearly all soils
• levels vary
(From: http://www.epa.gov/iaq/radon/zonemap.html)
Zone pCi/L
1
2
3
>4
2-4
<2
Radon: How it Enters Buildings
•
•
•
•
•
Cracks in solid floors
Construction joints
Cracks in walls
Gaps in suspended floors
Gaps around service
pipes
• Cavities inside walls
• The water supply
http://www.epa.gov/iaq/radon/pubs/citguide.html#howdoes
Radon: Reducing the Risks
• Sealing cracks in floors and walls
• Simple systems using pipes and fans
Sick Building Syndrome (SBS)
vs
Building Related Illness (BRI)
Sick Building Syndrome
• A persistent set of symptoms in > 20%
population
• Causes(s) not known or recognizable
• Complaints/Symptoms relieved after exiting
building
Complaints/Symptoms
•
•
•
•
•
Headaches
Fatigue
Reduced Mentation
Irritability
Eye, nose or throat
irritation
•
•
•
•
•
Dry Skin
Nasal Congestion
Difficulty Breathing
Nose Bleeds
Nausea
Building Related Illness
• Clinically Recognized Disease
• Exposure to indoor air pollutants
• Recognizable Causes
Clinically Recognized Diseases
–Pontiac Fever – Legionella spp.
–Legionnaire's Disease
–Hypersensitivity Pneumonitis
–Humidifier Fever
–Asthma
–Allergy
–Respiratory Disease
• Chronic Obstructive Pulmonary Disease
Ventilation
Movement of Air Into / Out of Homes
• Amount of air available to dilute
pollutants
– important indicator of the likely contaminant
concentration
• Indoor air can mix with outside air by
three mechanisms
– infiltration
– natural ventilation
– forced ventilation
Movement of Air Into / Out of Homes
• Infiltration
– natural air exchange that occurs between a building
and its environment when the doors and windows
are closed
– leakage through holes or openings in the building
envelope
– pressure induced
• due to pressure differentials inside and outside of the
building
• especially important with cracks and other openings in
wall
Movement of Air Into / Out of Homes
• Infiltration
– Temperature induced (stack effect)
• driven by air movement through holes in floors,
ceilings
• in winter, warm air in a building wants to rise, exits
through cracks in ceiling and draws in
Movement of Air Into / Out of Homes
• Natural ventilation
– air exchange that occurs when windows or doors are
opened to increase air circulation
• Forced ventilation
– mechanical air handling systems used to induce air
exchange using fans and blowers
• Trade-offs
– cut infiltration to decrease heating and cooling costs vs.
indoor air quality problems
Movement of Air Into / Out of Homes
• Infiltration rates
– Influenced by
• how fast wind is blowing, pressure differentials
• temperature differential between inside and
outside of house
• location of leaks in building envelope
Air Pollution Prevention
Specific Air Pollution Treatment
Technology
• Traditional
– Move factory to remote location
– Build taller smokestack so wind blows pollution
elsewhere
• New
– Biofiltration : vapors pumped through soil where
microbes degrade
– High-energy destruction: high-voltage electricity
– Membrane separation: diffusion of organic
vapors through membrane
– Oxidation: High temperature combustor
Absorption
Adsorption
Combustion
Cyclone
Filtration
Electrostatic Precipitator
Liquid Scrubber
Sulfur Dioxide
Control
http://www.apt.lanl.gov/projects/cctc/factsheets/puair/adflugasdemo.html
Air Pollution Results
Comparison of 1970 and 1999 Emissions
Number of People Living in Counties with Air Quality
Concentrations Above the Level of the National Ambient
Air Quality Standards (NAAQS) in 1999
Trends in Sulfur Dioxide Emissions Following
Implementation of Phase I of the Acid Rain
Program: Total State-level Utility SO2 (1980, 1990,
1999)
Fifty
Years
of
Air
Pollution
Figures are in millions of
metric tons per year
Mobile
Sources:
The Last
Ten Years
VOCs CO
NOx
-10%
-8%
PM10 SOx Lead
-3%
-29%
Percent reductions
shown are based on
estimates of tons/year
from mobile sources
over the 1981 - 1990
time period
-24%
-85%
63
Who is
Affected by
Air
Pollution?
Over 74 million people are
subjected to high levels of at
least one of these pollutants
22
Ozone CO
19
9
1
NO2
5
PM10 SO2 Lead
Millions of people living in counties
with air quality that exceeds each
NAAQS (1990 data)
1952 - Autos linked to air pollution
Milestones
in the
Control
of
Automotive
Emissions
1963 - Original CAA, PCV valves
1968 - HC & CO exhaust controls
1970 - CAA amendments, EPA formed
1971 - Evaporative controls
1972 - First I/M Program
1973 - NOx exhaust controls
1975 - First catalytic converters
1981 - New cars meet statutory limits
1989 - Volatility limits on gasoline
1990 - New CAA Amendments
• 1987 Montreal Protocol: CFC
emissions should be reduced by 50% by
the year 2000 (they had been increasing
3% per year.)
• 1990 London amendments:
production of CFCs, CCl4, and halons
should cease entirely by 2000.
• 1992 Copenhagen agreements: phaseout accelerated to 1996.
Goals of Kyoto Protocol
Reduction of greenhouse gases to below
1990 levels:
5.2% world wide reduction on average by 20082012
6% for Canada by 2008-2012
When sufficient countries ratify the
Protocol (at least 55 countries comprising at least
55% of emissions), Protocol comes into effect
USA - 25% of emissions
Kyoto Emissions Agreement