CE 326 Principles of Environmental Engineering
Air Pollution
Shane Rogers
What is air pollution?
Air pollution is the presence of ________________________, in quantities large enough to
________________________. – Noel de Nevers, Air Pollution Control Engineering



Not restricted to only human causes
Undesirable materials may damage:
o
o
o
o
Undesirable materials may also create aesthetic insults in the form of:
o
o
Many of these harmful materials enter the atmosphere form sources currently beyond human
control. However, in the most densely inhabited parts of the globe, particularly in the
industrialized countries, the principal sources of these pollutants are _______________. These
activities are closely associated with ________________________. To eliminate these activities
would cause such a drastic decrease in __________________________ that this action is seldom
considered. The remedy proposed in most industrial countries is to continue with the activities
and control the air pollutant emissions from them.
What are some examples of air pollution?
– things you are exposed to but can easily remove yourself from
 ____________ in basements
 ___________________ in a ____ or
the ________________________
 ____________________ from gasfired furnaces, stoves, portable
 __________________________ Town
heaters, etc. in the home
Engineering Building
 ______________________ (dirty air
 Others?
conduits, construction in buildings,
etc.)
– air pollution sources that affect small regions
 The ________________ in large cities
 ___________________ on Highway
30 by emissions form the cereal
 ______________ emitted from the
factory outside Cedar Rapids
_______________________
 Others?
 __________ from a _____________
or slaughterhouse
– air pollution that results in transport of pollutants over
large distances and result in global impacts
 Combustion byproducts that cause
 Pollutants that cause ______________
_________________
__________________________
 ______________ / _______________
 Others?
1
Major air pollution disasters of the 20th century (the big ones):
Meuse Valley, Belgium 1930 – SO2 emissions from coke ovens, steel mills, blast furnaces, zinc
smelters, glass factories and sulfuric acid plants was trapped in the 15-mile long Meuse Valley
by _____________________ causing more than ______ people to fall ill and a sulfuric acid mist
that killed _____. It was estimated that sulfur dioxide concentrations reached _________ µg/m3.
Donora, Pennsylvania 1948 (The Donora Death Fog) – Effluents from steel mills, a sulfuric
acid plant, and zinc production plant among others became trapped in a shallow valley inversion
to produce an unbreathable mixture of fog and pollution. About 6000 people (43% of the
population of Donora) suffered from sore throats, irritation of the eyes, nose, and respiratory
tract, headaches, breathlessness, vomiting, and nausea. There were 17 deaths in three days. It
was estimated that sulfur dioxide reached peak values of about 5,500 µg/m3.
Polluted yellow smog rolling into Donora
at noon on October 29, 1948. Reportedly,
by that evening people walking outside
could not see their hands in front of their
faces. A makeshift morgue was constructed
to deal with the dying that could not be
transported out of town because the smog
was too thick to drive through.
“The air was yellow and so full of sulfur, it
burned my eyes so badly that I had tears. My
eyes were burning like fire.” – Gladys
Schempp, resident
Source: Pennsylvania Department of Environmental Protection
Poza Rico, Mexico 1950 – An accident at a local factory that recovered sulfur from natural gas
released hydrogen sulfide into the ambient air over the course of only 25 minutes. The gas
spread under a shallow inversion mixing with foggy and calm conditions to kill 22 poeple and
hospitalize 320 more.
London, England 1952 (the Great Smog of London) – Anti-cyclonic or high pressure weather
with stagnating continental polar air masses trapped under subsidence inversions produced a
shallow mixing layer with an almost complete absence of vertical and horizontal air motion. The
availability of cheap coal for both factories and homes that lead to the infamous London ‘pea
soup’ smogs combined with the atmospheric conditions to form a dense smog in which the
concentrations of pollutants reached high values. Over the course of four days more than 4000
Londoners had died from the smog. Pollutant disasters with similarly high concentrations
occurred in 1957 – 1958 and again in 1962 – 1963, but the number of casualties during these
disasters was less.
Bhopal, India 1984 (Union Carbide incident) – Methyl isocyanate, a heavier than air gas, was
accidentally released over the course of four hours during the night from the Union Carbide
pesticide plant in Bhopal, India. The gas rolled into town, killing more than 2500 people and
injuring thousands more as they slept. Health effects of methyl isocyanate include leukorrhea,
pelvic inflammatory disease, excessive menstrual bleeding, suppression of lactation, stillbirths
and spontaneous abortions, and death by pulmonary edema bronchitis and pneumonia.
2
Lake Nyos, Cameron 1986 – Eruption under the lake releases CO2 killing 1700 people and their
livestock. Gasses continue to build under the lake and period releases are expected.
Chernobyl, Ukraine, USSR 1986 – Meltdown of a reactor core results in the release of a
radiation that kills 32, and of which the long-term effects on the cancer rates in the Ukraine,
Russia, and Europe are unknown. Lichens and sheep as far north as Norway were affected by
the release.
Kuwait Oil Fires, Early 1990s – 1991, Saddam Hussein orders the retreating Iraqi army to set
fire to more than 700 oil wells in Kuwait. The complete environmental and health impacts of
this release are still unresolved.
Sources: http://www.arl.noaa.gov/ss/transport/pgulf.html
http://www.members.tripod.com/KuwaiT_Q8/wpic.html
Global Air Pollution Issues:
Acid Rain
Normal rain picks up CO2 from the atmosphere, and thus is naturally acidic (pH~5.6). Average
rainfall over the United States has a pH ranging from 6.4 in the northeast to 4.2 in western
Pennsylvania, with readings as low as 3.0 recorded. Figure 4.15 in the text shows the 1985
contour map of pH in rain over the United States. Although natural systems have adapted to
slightly acidic rain (pH 5.6), lower pH rain can cause damage to:



Aquatic life - alter reproductive cycles in fish and/or release toxic soluble aluminum from
soils that otherwise would be insoluble.
Crops and forests – acid rain has caused extensive damage to forests in Europe and there
is concern similar results may occur in northeastern United States and Canada.
Building materials
What causes acid rain?
Chemical reactions in the atmosphere convert SOx, NOx, and VOCs to acidic compounds and
associated oxidants. For SO2 and NO, this starts with a slow oxidation step, followed by reaction
with available water to form an acid.
2NO + 2O2 → 2NO2
SO2 + O2 → 2SO3
4NO2 + 2H2O + O2→ 4 HNO3
SO3 + H2O → H2SO4
3
(nitric acid)
(sulfuric acid)
Source: Energy Educators of Ontario, 1993
Why does the pH of rain decrease towards the eastern seaboard?
The prevailing winds (jet
stream) moves from west to
east across the United States.
As pollution from combustion
processes (automobile
exhausts, coal-fired power
plants, etc.) is mixed into the
atmosphere, it is carried along.
It takes time for the initial
oxidation steps to proceed, and
therefore, the reaction with
water doesn’t occur until the
pollutants have had time to
travel. This is especially bad
for the northeast coast because
the soils have a relatively weak
buffering capacity, leaving
watersheds more vulnerable to
attack by acid rain.
Source: http://squall.sfsu.edu/crws/jetstream.html
What have we done to reduce the problem?



Clean Air Act of 1963 (see below)
1970 Clean Air Act Amendments
1990 Clean Air Act Amendments – 2 phase control program for SO2
4
Hole in the Ozone Layer
Although ozone is considered an air pollutant at ground level, in the stratosphere (10-50 km
above the earth’s surface) ozone is an important barrier to solar ultraviolet radiation. Without the
presence of the ozone layer to protect us from solar radiation, life on earth would not survive.
Dramatic thinning in the ozone layer can result in overexposure to UV radiation and increased
incidence of skin cancer. A dramatic thinning in the ozone in the lower stratosphere of
Antarctica was first noticed by a group of researchers from the British Antarctic Survey in the
1970s.
What causes the hole in the ozone layer?
1974, Molina and Rowland hypothesized that CFCs react with ozone in the stratosphere causing
a net depletative effect:
Normal Photoreactions with Ozone
O2 + hv → O + O
O + O2 + M→ M + O3
O3 + hv → O2 + O
Ozone Depletion by chlorofluoromethane
CCl3F + hv → CCl2F + Cl
Cl + O3 → ClO + O2
ClO + O → O2 + Cl
In this series of reactions, the chlorine atom generated by one molecule of chlorofluoromethane
continually cycles to remove more and more ozone from the ozone layer.
source: http://www.atm.ch.cam.ac.uk/tour/
2002
source: http://stacks.msnbc.com/news/815212.asp?cp1=1
5
What has been done to remedy this problem?
 1985 – Vienna Convention for the Protection of the Ozone Layer
o Nations agree to take appropriate measures for the protection of the ozone layer
o Encouraged research, cooperation, and exchange of information amongst
countries
 1987 – Montreal Protocol on Substances That Deplete the Ozone Layer
o Ratified by 36 countries
o Became effective in January 1989
o Reduce CFC production by 50 percent in 1998
o The problem is that CFCs are long lived in the atmosphere (CF2Cl2 = 110 years)
 1989 – Helsinki Declaration
o Phase out production and consumption of CFCs by 2000
o Phase out production and consumption of halons, CCl4, methyl chloroform as
soon as possible
o Commit to development of environmentally acceptable alternatives
o Train developing countries
 1990, 1992 – Strengthening of Montreal Protocol
o Ban production of CFCs, CCl4, and methyl chloroform as of January 1996
o Ban on halon production as of January, 1995
Greenhouse Effect
The greenhouse effect results from "the dirtying of the atmospheric infrared window" by some
atmospheric trace gases, permitting incoming solar radiation to reach the surface of the Earth
unhindered, but restricting the outward flow of infrared radiation. These trace gases absorb and
reradiate this outgoing radiation, effectively storing some of the heat in the atmosphere and
producing a net warming of the surface. This warming may affect:
 Water resources – quality and quantity, availability for irrigation, industrial use, etc.
 Coastal Resources – estimated 50 cm rise in sea level by 2100 could inundate 5,000
square miles of land and additional 4,000 square miles of wetlands in the US
 Health – heat stress, new breeding grounds for pests
 Agriculture and forests – increased temperatures and precipitation changes could increase
susceptibility to fires, disease, and insect damage
 Energy and Transportation – warmer temperatures increase cooling demand but reduce
heating requirements. Increased precipitation may cause flooding impacting waterways.
What are important greenhouse gasses?
 Water vapor (H2O)
 Carbon dioxide (CO2) from
combustion of fossil fuels and
deforestation
 Methane CH4
 Nitrous Oxide (N2O) (laughing gas)
 Chlorofluorocarbons (CFCs)
 Hydrofluorocarbons (HFCs)
 Perfluorocarbons (PFCs)
 Sulfure Hexafluoride (SF4)
 Tropospheric ozone (O3)
Source: USEPA
6
How do we measure the greenhouse effect and how significant are changes in greenhouse
gasses?


Direct measurements of the CO2 concentrations and global temperatures
Measurements of the CO2 concentrations in air trapped in ice cores in Greenland and
Antarctica
o Pre-industrial levels of CO2 were about 280 ppm
o Over the course of last 160,000 years, no fluctuations of CO2 have been larger
than 70 ppm.
Source: USEPA
What has been done to reduce greenhouse gas emissions?
 1987, 1989, 1990, 1992 - Phasing out of CFCs Montreal Protocol and Helsinki
Declaration
 1992 - Earth Summit, Brazil
o Developed countries asked to make sure their greenhouse gas emissions stayed at
1990 levels until 2000
o 150 countries signed the agreement
o Not a legally binding request
o Not all developed countries agreed to proposals
 1997 – Kyoto Protocol, Japan
o Conference of Governments tried to construct legally binding agreements about
what each country should do
o Each country to reduce greenhouse gas output by similar percentage (5.2% below
1990 levels before 2012)
o EU agreed to cut of 8%, US agreed to cut of 7%, Japan agreed to cut of 6%
o Russia and Ukraine agreed to stabilize at 1990 levels
o US opposed fines for countries not meeting emission requirements ($30/ton)
o To be enforced must be signed by 55% of countries or by countries responsible
for 55% of the 1990 greenhouse gas production
 2001 – George W. Bush rejects the Kyoto treaty then decides not to attend the Earth
summit (US is responsible for 25% of the worlds pollution)
 2002 - George W. Bush says he will not support a treaty that harms the US economy and
spurs concern with the environmentalists that other countries will follow suit
7
Air Pollution Legislation in the United States
History
 Prior to 1945 – factory smokestacks issuing thick plumes of smoke were seen as a sign of
prosperity. Industrial air pollution control efforts consisted of tort suits by neighbors of
the industries.
 Between 1945 and 1955 – Local efforts to control air pollution, notably in Pittsburgh, Los
Angeles, and St. Louis.
 1955 – Air Pollution Control Act
o First federally enacted air pollution legislation in the United States
o Narrow in scope / potential – Federal government not to encroach on states’ rights
o Research on the effects of air pollution by the U.S. Public Health Service
o Provision of technical assistance to the states by the federal government.
o Training of individuals in the area of air pollution
 1960, 1962 - Air Pollution Control Act Amendments
o Congress directed the Surgeon General to conduct a study of motor vehicle
exhausts in terms of their effects on human health
 1963 - Clean Air Act
o Provision of federal financial aid for research and technical assistance
o Federal jurisdiction only in the case of interstate commerce
o Encouraged state, regional, and local programs for control and abatement of air
pollution and its subsequent enforcement (only 13 states had laws at this time for
controlling state-wide air pollution)
o Initiated efforts to control air pollution from all federal facilities
o Development of air quality criteria
o Encouraged automotive companies and fuel industries to prevent pollution
o Constructed a committee to monitor progress toward control and indicate areas
where added research and development were essential
 1965 – Motor Vehicle Air Pollution Control Act
o Enforced automobile emissions standards for carbon monoxide and hydrocarbons
on a national basis (adopted the California standard)
o Stipulated that controls could be tightened as technological advances became
more available in conjunction with reasonable costs
 1967 – Air Quality Act
o Designated air quality control regions (AQCRs) within the United States.
Evaluation of each to determine the nature and extent of the air pollution problem
o Issued Air Quality Criterias (AQCs) for specific pollutants that have an
identifiable effect on human health and welfare
o Develop and issue information on recommended air pollution control techniques
o Required fixed time schedule for state and local agencies to establish air quality
standards consistent with air quality criteria.
 States could set more stringent standards
 If states did not act, standards could be set for them
o Was not implemented according to required timetable. Only 108 AQCR were
designated by 1970. Setting up AQCRs was too complex
 1970 – Clean Air Act Amendments
o Created the USEPA (United States Environmental Protection Agency)
o Major goal was to achieve clean air throughout the nation by July, 1975
o Established (NAAQS) National Ambient Air Quality Standards
8






o Established New Source Performance Standards (NSPSs)
o Established National Emission Standards for Hazardous Air Pollutants
(NESHAPs)
o Established a criteria for designating AQCRs
o State Implementation Plans (SIPs) to meet standards were given a timetable
o Established fines and criminal penalties for violation of implementation plans,
emissions standards, performance standards
o Established tougher automobile emissions standards
o Established aircraft emissions standards
1976 – Lead added to the list of criteria pollutants
1979 – Photochemical oxidants standard revised and restated as ozone
1983 – Hydrocarbon standard reviewed and withdrawn
1987 – Total suspended particles (TSP) standard reviewed and revised to only include
particles with an aerodynamic particle size of less than or equal to 10 µm and referred to
as the PM10 standard
1990 – Clean Air Act Amendments
o Further defines the roles of federal and state governments
o Initiated a permit program for larger sources that emit pollutants into the air
o Interstate commissions on air pollution control to develop interstate strategies to
clean up air pollution
o Addresses international air pollution (pollution moving to and from the US,
Canada, and Mexico)
o New enforcement laws allow EPA to fine violators
o Set more realistic deadlines for attainment
o Implement market-based approach/incentive program for cleaning up air pollution
o HAPs list was expanded to include 189 pollutants and gives EPA the flexibility to
add more if necessary
o Requires maximum avail control technology for HAPs
o Requires industry to produce plans to prevent accidental releases of HAPs
o Strict new laws on mobile sources like fuel regulations and control technologies
1997 – PM2.5 standard was added
Important Concepts of the Clean Air Act (CAA)
The EPA has broken the nation into over 240 Air Quality Control Regions (AQRs). Air
pollution is monitored in each of these regions.
2 types of pollutants
 Criteria Pollutants - pollutants for which there is some threshold concentration that is safe
for the public
o Criteria pollutants are regulated by National Ambient Air Quality Standards
(NAAQS) set by the USEPA. These are maximum concentrations of pollutants
that are in the ambient air within an AQR that are protective of human health,
welfare, visibility, and property damage. NAAQS can be either:
 Primary standards – NAAQS of a pollutant based upon health-related
criteria, considering the health of “sensitive” populations such as
asthmatics, children, and the elderly.
 Secondary standards – NAAQS of a pollutant based upon protection of
public welfare, including protection against reduced visibility, damage to
animals, crops, vegetation, and buildings (property damage).
9
o Attainment areas = AQRs where air quality meets or exceeds primary standards
o Non-attainment areas = AQRs where air quality doesn’t meet primary standards
 Hazardous Air Pollutants (HAPs) – pollutants for which there is no demonstrable safe
threshold concentration
o HAPs are regulated by National Emmissions Standards for Hazardous Air
Pollutants (NESHAPs). These are standards based upon risk models and some
perception of acceptable increased risk of toxic or carcinogenic effects, usually
between one in ten thousand to one in a million. We will talk about these later.
o The USEPA has constructed a list of 189 chemicals that they consider HAPs.
Several other chemicals are being constantly evaluated for inclusion on the list.
NAAQS
POLLUTANT
STANDARD
VALUE *
STANDARD
TYPE
Carbon Monoxide (CO) –binds with hemoglobin in the blood resulting in asphyxiation, perception and
learning impairment at low exposures (50 ppmv for 8 hours), death in minutes at >5000ppmv
8-hour Average
9 ppm
(10 mg/m3)
Primary
3
1-hour Average
35 ppm
(40 mg/m )
Primary
Nitrogen Dioxide (NO2) – 5ppmv exposure for 15 minutes causes irritation of respiratory tract.
Prolonged exposure could cause pulmonary edema
Annual Arithmetic Mean
0.053 ppm
(100 µg/m3)
Primary & Secondary
Ozone (O3) – eye irritation at 0.1 ppmv, cough and chest discomfort at 0.3 ppmv
1-hour Average
0.12 ppm
(235 µg/m3)
Primary & Secondary
3
8-hour Average **
0.08 ppm
(157 µg/m )
Primary & Secondary
Lead (Pb) – cumulative poison, low blood levels cause fatigue, irritability, mild headache, higher levels
cause constipation and abdominal cramps, acute exposures result in convulsions, coma, cardiac
arrest,and death. Chronic exposures may result in brain damage, seizures, mental incompetence,
aggressive behavious, and eventual paralysis.
Quarterly Average
1.5 µg/m3
Primary & Secondary
Particulate (PM 10) – increased risk of respiratory, cardiovascular, and cancer-related deaths, as well
as pneumonia, lung function loss, hospital admissions, and asthma.
Annual Arithmetic Mean
50 µg/m3
Primary & Secondary
3
24-hour Average
150 µg/m
Primary & Secondary
Particulate (PM 2.5) – possibly a major contributor to elevated death rates in polluted cities
Annual Arithmetic Mean **
15 µg/m3
Primary & Secondary
3
24-hour Average **
65 µg/m
Primary & Secondary
Sulfur Dioxide (SO2) – increased respiratory symptoms in susceptible individuals. Effects on
pulmonary function at concentrations approaching 200µg/m 3
Annual Arithmetic Mean
0.03 ppm
(80 µg/m3)
Primary
3
24-hour Average
0.14 ppm
(365 µg/m )
Primary
3-hour Average
0.50 ppm
(1300 µg/m3)
Secondary
** 1999 federal court ruling blocked these standards, USEPA is trying to reverse the decision
What effects have the CAA and CAA amendments had on pollution in the US?
10
Six Principle Pollutants:
source: USEPA
Acid Rain:
11
Toxic Air Pollutants:
Source: USEPA
12