New York Medical College Dispersal of Air Pollutants Essay

ENV 5001Air Pollution
Regulations
Air Pollution – An Introduction
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ENVM-6009 Course Topics
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Introduction, History and Chemistry of Air Pollution
Health Effects of Air Pollution
Air Pollution Sources
Dispersion Modeling and the Fate of Air Pollution
Measuring Air Pollutants
Risk Assessment and Air Pollution Regulations
Odors
Air Pollution Control Technologies
Asbestos
Indoor Air Quality (IAQ) and Radon
Ozone Depletion and Natural Pollutants
Acid Rain and Climate Change
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Dilemma
• How can society fully function and also minimize the adverse public
health effects of air pollution?
• Problem: Many chemicals are necessary to produce the items we need
• Air toxics are emitted in association with our daily activities (i.e. driving a car)
and cannot be banned. How can we regulate such emissions to preserve
public health?
• Require facilities to use the best technologies to minimize emissions
• Problem: Reduced rate of emissions is not a zero rate and may still cause
harm
• Require companies to demonstrate that ground-level concentrations
will not cause a public health problem
• Problem: What about hypersensitive members of the population. Where do
we draw the line?
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Regulation of Air Pollution
Goal:
To minimize the health effects and the environmental impact
of air pollution.
Required Action:
1. Minimize the overall quantity of pollutants in the air
2. Minimize the concentration of those pollutants at the
ground level.
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Regulation of Air Pollution (cont’d)
How do we go about regulating air pollution?
• Health effects of emissions
• Availability of control technology
• Economics
• Fairness
• Balance between all of these?
• If an emission standard is too stringent, it may drive facilities to shut down,
causing unemployment.
• If too lax, then health goals may not be met.
• Ever present limitations due to the availability of appropriate technology.
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Regulation of Air Pollution (cont’d)
• How much pollution is too much? Where do we
draw the line?
• We need to determine what the level of air pollution
is before we observe an adverse effect on public
health and the environment.
• How do we determine that?
• We need to assess the risk.
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Risk Assessment
Risk:
• The probability of an adverse outcome
• Internationally, this is the definition of a “hazard”
• In the US, a “hazard” refers to an intrinsically harmful property.
Risk Assessment:
• The systematic process of determining the probability and
magnitude of that adverse outcome.
• Includes both qualitative and quantitative information
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Risk Assessment (cont’d)
Four Stage Process:
1.
2.
3.
4.
Hazard Identification
Hazard Assessment
Exposure Assessment
Risk Characterization
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Hazard Identification
• A qualitative evaluation of the available data in order
to classify the hazard.
• Methods
• Structure Activity Relationships
• In Vitro Studies
• Epidemiology
• Animal Studies
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Structure/Activity Relationships (SARs)
• Recall:
• Water solubility of SO2 vs NOx from Health Effects
lecture
• Affects absorption/dose
• Chemical Structure
• Comparison to known toxic agents
• Similar activity/effect?
• Useful in cosmetics industry
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SARs (cont’d)
• e.g. Dioxin Like Compounds (DLCs)
• https://ordspub.epa.gov/ords/guideme_ext/f?p=guideme:gd:::::gd:dioxin
• 2005 World Health Organization (WHO) dioxin toxicity equivalence factors
(TEFs) to calculate dioxin toxicity equivalence (TEQ)
• Rates toxicity of DLCs to that of 2,3,7,8 Tetrachlorodibenzodioxin (TCDD)
• 0.4 ng/dscm
Cl
Cl
Cl
Cl
3,3’,4,4’ Tetrachloro PCB (77)
2,3,7,8 Tetrachlorodibenzofuran
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SARs (cont’d)
Splenda
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In Vitro Studies
• Cell and tissue culture
• Metabolism/biotransformation of toxins is often lacking
• Not very useful for as a starting point.
• Used more in the determination of the mechanisms of
toxicity
• e.g. after a target organ is identified
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Epidemiology
• Evaluate exposure and adverse effects in human population
• Primarily Retrospective
• Can be prospective following a release and exposure.
• Decent starting point
• Not controlled for a particular toxin
• Cause and effect?
• Other variables?
• Other toxins present
• (e.g. Paraquat causes pulmonary fibrosis via an ingestion route)
• Life style factors?
• (i.e. Diet, smoking)
• Genetics
• Latency period
• More qualitative than quantitative
• Dose?
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Animal Studies
• Animal exposure for the determination of effects
• Often given far higher doses than we humans would be subjected to
• e.g. saccharin vs sucrose
• Extrapolation to humans?
• Monkeys provide a good model of the human respiratory system
• Extremely expensive to house and test
• Rats lack our respiratory bronchioles and are obligate nose breathers
• Rabbits and guinea pigs predicted human sulfuric acid response.
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Hazard Assessment
1. Establish a Dose Response Relationship
2. Define acceptable dose
• Non-cancer (those with a known threshold)
• Determine the Reference Concentration (RfC)
• Safe
• Cancer
• Determine dose of acceptable risk
• No “safe” dose/concentration
• Accept chance of 1 in 1,000,000 (106) Excess Cancer case
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Dose Response
NOAEL – No Observed
Adverse Effect Level
LNT
LOAEL – Lowest Observed
Adverse Effect Level
LD50 – Lethal Dose for 50%
of the population
LNT – Linear No Threshold
DNEL – Derived No Effect
Level (also RfD/RfC)
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Dose Response (cont’d)
• Determine NOAEL/NOEL
• Determine LOAEL/LOEL
• RfC is derived from NOAEL/NOEL
• Sometimes NOAEL/NOEL is not determined and
LOAEL/LOEL must be used instead.
• To obtain RfC, need to adjust NOAEL/NOEL or LOAEL/LOEL
to account for extrapolation from animal studies and other
potential biases
• Divide by appropriate Uncertainty Factors (UFs) and a Modifying
Factor (MF) as a buffer.
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Uncertainty Factors (UFs)
• Individual UFs are usually a factor of 10
• May also be a factor of 3
• They’re multiplicative and may therefore balloon several orders of
magnitude before the composite UF is reached.
• Usual range is 100 – 1,000 however UF’s of 10,000 are not unheard
of.
• Each of the following factors are associated with a UF of 10:
1.
2.
3.
4.
5.
Data gaps
Use of LOEL instead of NOEL
Lack of chronic toxicity data
Interspecies extrapolation
Intraspecies variation (to account for more sensitive groups)
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UFs (cont’d)
• A Modifying Factor (MF) may also be included
• MFs range from 1 (no change) to 10
• Accounts for exposure route issues and potential
differences in absorption and metabolism.
• Therefore the RfC = NOAEL/(UF x MF) where the UF
is all the UFs multiplied by each other.
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Integrated Risk Information System (IRIS)
• USEPA’s Risk System
• https://www.epa.gov/iris
• Contains Inhalation Guideline Concentrations (RfCs) for hundreds of
HAPs.
Chemical
RfC
(mg/m3)
Composite
UF
NOEL
(mg/m3)?
Acetaldehyde
0.009
1000
9
Benzene
0.03
300
9
Dichloromethane
0.6
30
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• Here, the Composite UF represents the product of the UFs (with MFs of 1)
• Note the potentially vast difference and how it impacts the RfC?
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Cancer
• The process regarding cancer causing agents is somewhat
different
• Cancer is deemed to have no threshold
• Risk associated with every exposure (Linear No Threshold (LNT) Theory)
• For the general public, the acceptable risk has been set at:
• One Excess Cancer in 1,000,000 (Risk = 1 x 10-6) over a lifetime
• The EPA uses the slope of the LNT curve to establish the Slope
Factor (SF) which it refers to as the Inhalation Unit Risk (IUR) of
Excess Cancers per each µg/m3 of a particular chemical inhaled
for their entire life.
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Inhalation Unit Risk (IUR)
• For dichloromethane (aka methylene chloride) the IUR is 1 x 10-8 per
µg/m3
• This means there’s a risk of just one Excess Cancer in 100,000,000 people for
every µg/m3.
• This therefore translates to one Excess Cancer in 1,000,000 people for every
100 µg/m3
• On the other hand, for Benzo[a]pyrene, the IUR is 6 x 10 -4 per µg/m3
• This means there’s a risk of 6 Excess Cancers in every 10,000 people for every
µg/m3.
• This therefore translates to one Excess Cancer in 1,000,000 for every 0.0017
µg/m3.
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Exposure Assessment
• The best way to assess overall exposure is via continuous
environmental monitoring of the various pollutants to establish the
average concentrations.
• Modeling can also be done but there’s room for error.
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Risk Characterization
• Concentrations from the Exposure Assessment are then
compared to the applicable RfCs and IURs determined
during the Hazard Analysis.
• If the units are they same (e.g. µg/m3), all we need do is
divide the that exposure concentration by the RfC.
• If the value is below 1 then the exposure concentration is
acceptable
• If it’s greater than 1 then it’s too high and if it’s around 1 it’s
bordering on a potential problem.
• This forms the basis of the EPA regulations.
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Risk Assessment Resources
• https://www.epa.gov/risk/risk-assessment-guidance
• https://rais.ornl.gov/index.html
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Workplace Exposure
• Through such Risk Assessment, the American Conference of
Government Industrial Hygienists (ACGIH) has put out Threshold
Limit Values (TLVs) for many chemicals found in the workplace.
• These TLVs are based on a Time Weighted Average (TWA) of 8 hours
per day (40 hours per week) and define the safe concentration.
• The Short Term Exposure Limit (STEL) is a higher exposure permitted
for just 15 minutes.
• OSHA’s Permissible Exposure Limits (PELs) and Excursion Limits, for
the most part, perfectly line up with these TLVs and STELs,
respectively.
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Regulations
• USEPA – Established Dec. 2, 1970
• U.S. Clean Air Act (CAA) of 1970 – Dec. 31, 1970
• National Ambient Air Quality Standards (NAAQS)
• Criteria Pollutants: CO, Pb, NO2, O3, PM2.5 and 10, SO2
• National Emission Standards for Hazardous Air Pollutants
(NESHAPs)
• Phasing out lead from gasoline,
• Initial standards for hazardous air pollutants.
• Consistency of Air Quality Regulations
• “Battle” between individual regulations by each state vs. federal
rules (conformity of all states)
• Mandates states to develop uniform air quality rules meeting
minimum requirements
• Called State Implementation Plans (SIPs)
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Regulations (cont’d)
• 1977 –Amendment of Clean Air Act. Introduced New Source Review
(NSR) legislation to limit increases of pollutants by new or modified
plants, even tougher than criteria pollutant standards.
• 1990 –Latest amendment of Clean Air Act.
• Introduced more comprehensive hazardous air pollution standards, first
uniform permitting standards, acid rain program, stratospheric ozone
program.
• Establishes minimum uniform requirements for state permitting programs
(e.g. “Title V”)
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1990 (cont’d)
• Upgrade of National Emission Standard for Hazardous Air Pollutants
(NESHAP) program Raised list of HAPs from about 8 to 189.
• CAA Section 112 (d)
• Maximum achievable control technology (MACT) standard
• Performance criteria designed to decrease air toxic emissions.
• Both New and Existing Sources
• “Control Technology” includes processes, methods, systems, and
techniques.
• Technology and work practices producing the lowest HAPs used to set the
standards for the rest of the industry.
• Must not be less than the average emission level achieved by controls on the best
performing 12 percent of existing sources, by category of industrial and utility sources.
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Ambient Concentrations
• The USEPA reviewed hundreds of public health and animal
studies in order to determine the NAAQS for the Criteria
Pollutants.
• Vulnerable populations were accounted for
• (e.g. through UFs and MFs).
• The USEPA reviews these determinations and changes the
NAAQS regularly as warranted when new data comes to
light.
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NAAQS
https://www.epa.gov/criteria-air-pollutants/naaqs-table
Pollutant
Primary/
[links to
historical tables
Secondary
of NAAQS
reviews]
Carbon Monoxide
primary
(CO)
primary and
Lead (Pb)
secondary
primary
Nitrogen Dioxide
(NO2)
Averaging Time Level
Form
8 hours
9 ppm
1 hour
35 ppm
Not to be exceeded more than once
per year
Rolling 3 month
average
0.15 μg/m3 (1)
Not to be exceeded
1 hour
100 ppb
98th percentile of 1-hour daily
maximum concentrations, averaged
over 3 years
1 year
53 ppb (2)
Annual Mean
8 hours
0.070 ppm (3)
Annual fourth-highest daily maximum
8-hour concentration, averaged over
3 years
primary and
secondary
primary and
Ozone (O3)
secondary
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NAAQS (cont’d)
https://www.epa.gov/criteria-air-pollutants/naaqs-table
Pollutant
Primary/
Averaging
Time
Level
primary
1 year
12.0 μg/m3
secondary
1 year
15.0 μg/m3
24 hours
35 μg/m3
98th percentile, averaged over 3
years
24 hours
150 μg/m3
Not to be exceeded more than
once per year on average over 3
years
primary
1 hour
75 ppb (4)
secondary
3 hours
0.5 ppm
[links to historical
tables of NAAQS Secondary
reviews]
PM2.5
primary and
Particle
Pollution
(PM)
secondary
primary and
PM10
secondary
Sulfur Dioxide (SO2)
Form
annual mean, averaged over 3
years
annual mean, averaged over 3
years
99th percentile of 1-hour daily
maximum concentrations,
averaged over 3 years
Not to be exceeded more than
once per year
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Nonattainment
Monitoring of Air Quality
• The USEPA and the states operate thousands of
monitors to gather real-time ambient levels of these
criteria pollutants.
• Why?
• To determine whether areas around the country are
in or out of attainment with the allowable ambient
air quality levels just listed.
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Nonattainment (cont’d)
Promulgated rules:
• Regulate emissions to maintain attainment or
• Reduce emissions to achieve attainment in nonattainment
areas
• Regulations are stricter in areas of nonattainment compared to
attainment areas.
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Nonattainment (cont’d)
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Nonattainment (cont’d)
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Nonattainment (cont’d)
Can a facility pollute as much as it wants as long as area does not
become nonattainment?
• In the 1970s, a company wanted to build a factory in Yellowstone
National Park without any air pollution control (APC) equipment.
• They calculated that emissions would not cause the ambient air to exceed the
NAAQS.
• The USEPA agreed; its job, according to CAA, was to simply enforce the
NAAQS.
• The US Supreme Court then ruled that USEPA was also obligated to
protect the environment from degradation
• Led to the “Prevention of Significant Deterioration” (PSD) rules with the
hopes of preventing an attainment area from slipping into nonattainment.
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Prevention of Significant Deterioration (PSD)
• PSD mandates that new facilities, or existing facilities proposing a
major emissions increase of an attainment compound, install APC
equipment.
Or
• Prove through dispersion modeling, or through calculations, that the
rise in ground level concentrations of the pollutants (the
“deterioration” of the local air) will be minimal.
• Problem, still allows some deterioration
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PSD (cont’d)
New Source Review (NSR)
• Set of rules for regulatory agencies to allow the construction and operation of
new sources of air emissions.
• Includes PSD requirement.
• Applies to new or expanded sources covering pollutants already in attainment
with the area’s NAAQS
• “Nonattainment NSR” applies to new facilities or proposed expansions in areas
already nonattainment with a NAAQS.
• Much more stringent standards, including the most stringent emission rate standards
and paying for credits of emission reductions achieved elsewhere.
• If a company proposes to expand operations in an ozone non-attainment area, and after
application of most stringent APC, is still raising VOC emissions by 100 TPY, then
company must buy credits from others who have reduced VOC emissions
• Usually 30% excess (130 tpy)
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New Source Performance Standards (NSPS)
• Independent of an area’s attainment status, regulations require new
sources of emissions to meet minimum emission standards
“Reasonably” Available Control Technology (RACT)
• Based on the theory that if a company has money to invest in upgrades, it can
also invest in reasonable APC equip.
• Federal New Source Performance Standards (NSPS), provides “level”
playing field for all new or modified processes in a given industry.
• Dozens of NSPS.
• NSPS allows “grandfathering”, exempting existing facilities, as long as
they are not modified, on the theory that they will eventually all need
to be modernized (e.g. when equipment breaks down).
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Grandfathering
Two problems with grandfathering:
• What constitutes a “modification” that would make a facility ineligible
for grandfathering?
• Grandfathering encourages old facilities to remain as they are and not
upgrade their equipment nor install APC devices.
• Often polluting the most
• Encourages them not to modernize.
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Pollutant Transport
• Pollutants can be transported hundreds of miles away and affect
people or the environment in another state or region of the country.
• How do we regulate this? How can we prove that a certain effect on a
person, forest, or lake is due to a particular facility hundreds of miles
away?
• The courts have ruled that the EPA can regulate pollutants that are
transported regionally.
• The Acid Rain Rules of the 1990 CAA.
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Command and Control
• Historic Solution: Effective regulations to reduce specific air pollutants
emissions and/or ground-level concentrations enforced by
government agencies to eliminate or reduce any adverse public
health effects from those pollutants
• Command and Control:
• Regulatory agency sets emission limits believed to adequately reduce health
effects
• The affected facility must achieve it – no matter how difficult or costly.
• Affected facilities may have little flexibility and be required to commit
to expensive APC equipment and costly monitoring equipment in
order to prove compliance.
• Guilty until proven innocent?
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Fines
• Economic penalties could allow governments to collect
enough money to offset pollution associated health care
costs and lost income taxes and lower productivity.
• Historically, Gov’ts have not levied large penalties.
• Companies have historically passed along fees and fines to
the consumer, which do not raise overall product prices
greatly. Therefore, large fines may disproportionally hurt
smaller firms.
• Shouldn’t fines be structured to be more expensive than the
fix?
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State and Local Regulations
• States can enforce federal regulations (and
receive Federal Funding to do so) by
promulgating state regulations meeting the CAA
requirements.
• States are encouraged to go beyond the
regulations and have stricter standards or
regulate additional pollutants.
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Connecticut MASC
MASC = Maximum Allowable Stack Concentration
• Mandatory program, but contains several exceptions, such as
grandfathering.
• Contains short-term and annual concentration standards for many
hundreds of air toxics.
• Requires affected facility to work backward from an acceptable risk at
ground level to a stack concentration to ensure standard is met. Contains
simple, conservative modeling equation to determine the MASC.
• Facility compares site-specific calculated MASCs to the standards to
determine whether emissions are acceptable.
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State and Local Regulations (cont’d)
• Some states and municipalities have their own air
toxics lists.
• Most are more extensive than the federal list.
• What if a company wants to use and emit a
compound that a state never got around to putting on
their list?
• Several states require an applicant to either supply their
own toxicity study or prove that the compound is not or
only mildly toxic.
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New York State Division
of Air Resources (DAR)
• New York State’s DAR-1 is an extensive list of air pollutants with both short term and
annual guideline concentrations (SGCs and AGCs):
• https://www.dec.ny.gov/docs/air_pdf/dar1.pdf
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Permitting
• How do we know what a facility is emitting?
• All states mandate that facilities apply for and are issued air permits
that list maximum allowable emission rates for all regulated
pollutants and processes
• In addition, the permit should list all applicable air regulations that the facility
or process must comply with.
• Enforcement possible for facilities that exceed an emission limit found
in a permit.
• Meant to be transparent
• Permit information and emission limits are available to the public.
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Title V Permitting
• States with strict requirements felt it was at a disadvantage against
states with more lax rules.
• Title V establishes minimum conditions for state permitting programs.
• All Title V permits must:
• Contain all regulatory citations in the single document
• List all monitoring, recordkeeping, and reporting requirements to
demonstrate continuous compliance
• Be transparent to public
• Be signed by a high level “Responsible Official” who could serve jail time for
submitting false data (even if “RO” does not know the details).
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Title V Permitting (cont’d)
• Only “Major” facilities must obtain a Title V Permit.
• A major source has actual or potential emissions at or above the
major source threshold for any “air pollutant.”
• The default threshold for a major source for any air pollutant is
100 tons/year.
• Lower thresholds apply in non-attainment areas but only for the
non-attained pollutant.
• Major source thresholds for “hazardous air pollutants” (HAP) are
10 tons/year for a single HAP or 25 tons/year for any combination
of HAPs.
• The USEPA diligently reviews whether or not State air permits
meet Title V.
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Questions?
• Questions? Head on over to the Q & A Forum under
Discussions in Canvas and ask them there so that
everyone can benefit from the answers.
• Make sure to include the Lecture’s Title and the Slide #
(bottom right corner)
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a
You performed a dispersion model for a chemical manufacturing plant’s newly engineered process
and the ground-level impacts of a key Hazardous Air Pollutant (HAP) exceeds the allowable
concentration. Name two (2) reasonable methods you would recommend to the manager of the facility
to hopefully reduce those ground-level impacts to an acceptable level (Note: you cannot install Air
Pollution Control (APC) equipment (which we haven’t yet covered) nor change the chemical process
in the plant, it’s all about dispersion).