Classification of Air Pollutants
Air Pollutants
Criteria PollutantsNOx, Sox, PM, CO,
Ozone, Lead
Mobile PollutantsCO, VOCs, NOx,
Sox, Lead
Acid Rain PrecursorsSox, NOx
Air ToxicsNESHAPS, HAPs,
TAPs, 112r Substances
Ozone DepletersCFCs, HCFCs,
Halogenated VOCs
Health EffectsIrritant, Edema, Emphysema
Permits - Title V, NSPS,NSR
Standards - NAAQS
Control – Attainment, SIPs
Source control LAERBACT
Emission Cap and TradeProgram
Health Effects –Toxics, Mutagens,
Carcinogens
Standards –Threshold Emission
Limits
Permits – Major Source =
10/25 tonsTitle V
Control –MACT, RMPs
Criteria Pollutants
Pollutants for which National Ambient Air Quality Standards (NAAQS) have been established:
1. Particulates (PM10)2. Sulfur Oxides (SOx)3. Nitrogen Oxides (NOx)4. Carbon Monoxide (CO)5. Photochemical Oxidants (Ozone)6. Lead
Toxic Pollutants
Pollutants hazardous to health or the environmentbut not regulated as criteria pollutants:1. Mercury2. Asbestos3. Arsenic4. Benzene5. Radon6. Vinyl Chloride7. Beryllium8. Coke Oven Emissions9. 188 compounds designated by EPA as “Hazardous Air
Pollutants” or HAPs.10. North Carolina has identified 105 “Toxic Air Pollutants” with
acceptable ambient levels or AALs.
Global Pollutants
Pollutants that because of their persistence ordistribution have a global impact on air quality:
• Chlorofluorocarbons – Stable “freons” that once in the stratosphere breakdown Ozone.
• Carbon dioxide – Major substance related to the global “greenhouse effect”.
Regulation of Air Pollution
Hazardous Air Pollutants - HAPs: 188 Specific compounds
Definition = A substance when released to the atmosphere can cause significant harm to human health or the environment; includes
Particularly or extremely toxic substances Carcinogens Mutagens
Regulation of Air Pollution
Hazardous Air Pollutants – Sources
Major Source = Any stationary source that emits 10 tons or more per year of any single HAPs or 25 tons or more per years of all HAPs.
Area Source = Any stationary source of HAPs that is not a major source.
Regulation of Air Pollution
Hazardous Air Pollutants – Emission Control
US EPA required to list: categories of major sources, categories of area sources warranting regulations, and national emission standards.
Maximum Achievable Control Technology or MACT = For a major source in a particular category – The average emission
limitations achieved by the best performing 12% of existing sources or
The average emission limitation achieved by the best performing 5 sources if there are fewer than 30 sources in a given category
HOW HAPS AND TAPS ARE REGULATED
Emission limits for major or area sources are established and regulated by air permitting process
Sources (major and area) of HAPs must install MACT to meet HAP emission reduction requirements
All sources of NC TAPs must comply with NC TAP regulations
CONTROL OF HAZARDOUS AND TOXIC AIR POLLUTANTS
NC Toxic Air Pollutants TAPS Program Compliments the Clean Air Act Program for Hazardous Air Pollutants (HAPs)
Federal HAP Program is technology-based and requires Maximum Achievable Control Technology (MACT)
NC TAP Program is health-based and has an acceptable ambient concentration
Regulation of Air Pollution
North Carolina – Toxic Air Program
A health-based toxic air pollutant control program that regulates 105 air pollutants emitted from stationary sources.
Emissions of toxic air pollutants must be reduced such that the resulting modeled ambient air levels are below health-based acceptable ambient air levels at the property line.
Regulated facilities must submit a complete air toxic emissions report once every 3 years.
NC TAP REGULATORY PROGRAM
The Science Advisory Board sets an exposure limit – the Acceptable Ambient Limit (AAL)
The NC Division of Air Quality (DAQ) is responsible for enforcing the AAL through air permits:
The NCDAQ sets an emission limit from emission sources above which the ambient concentration will be exceeded
This emission limit (rate) is called the Toxic Permitting Exemption Rate, or TPER
NC TOXIC AIR POLLUTANTS
Each TAP has an AAL-Acceptable Ambient Level established by a State Science Advisory Board (SAB)
SAB composed of physicians, toxicologist and other scientists The AAL is the concentration limit for exposure of the public Some pollutants have hourly limits, others have daily or
annual Examples
HCl: Hourly LimitCarbon disulfide: 24-hour limitEtO: Annual limit
Hourly = Acute irritant 24-hour = Chronic irritant Annual = Cancer causing
EXAMPLE OF STEPS INVOLVEDETHYLENE OXIDE
Identify all possible sources of EtO Determine the emission rate of each source. In this case – 7 EtO
sterilizers- number of cycles per year- emission of EtO per cycle
Obtain precise emission parameters- stack height, location- exhaust temperature, velocity, etc.
Build the computer dispersion model- topography- all buildings, structures, etc.- all emission information
Obtain NCDAQ approval of all modeling information Run the emission model (Aeromod) for 5 consecutive years of
meteorological data. Use results of the worst-case year and must be below Acceptable Ambient Limit.
Apply for air permit with emission limits
AIR PERMITTING OF TOXIC AIR POLLUTANTS
If facility’s emissions of any TAP are above the TPER, facility must:
Perform dispersion modeling to demonstrate that the off-site concentration due to the facility emissions will be below the Acceptable Ambient Limit
Submit application for air permit
Maintain records to demonstrate it always operates within the emission limits of its air permit
Modeling Air Toxics – Ethylene Oxide
Meteorological Data
Constituent Emission Rate
Stack Parameters Temperature Exit velocity Stack diameter Stack height
Modeled air concentration –expressed as asingle point of maximum impactor as an isopleth
Air model(Aeromod)
ETHYLENE OXIDE EXAMPLE
The TPER for EtO is 1.8 lbs/yr
The EtO potential emissions (assumes every sterilizer runs 24/7) were estimated at 18.02 lbs/yr – Therefore:
Constructed and ran computer model and applied for air permit
Modeling results: - Allowable Ambient Limit (AAL) = 2.7 x 10-5 milligrams/m3
- Highest concentration = 8.47 x 10-6 milligrams/m3
- Highest concentration ~ 31% of AAL at one spot- Vast majority of area is less than 10% of the AAL
Figure shows modeling results in micrograms/m3 (µg/m3)e.g. kellygreen = 0.003 µg/m3 = 0.000003 milligrams/m3 = 11% of AAL
Release Prevention and Control
Regulatory Actions Aimed towards Emergency Preparedness to Prevent and Mitigate Releases
.
Section 302 – Identification of Extremely Hazardous Substances stored, processed or otherwise used above threshold planning quantities
Section 304 – Notification of reportable releases of CERCLA hazardous substances or Section 302 Extremely Hazardous Substances above reportable quantities.
Section 311 – Initial report to local fire department, LERC, and SERC of hazardous substances used or stored on site.
Section 312 – Annual report on the presence of hazardous substances used or stored on site
Section 313 – Toxic Release Inventory: Facilities with SIC codes 20-39 who manufacture or process more than 25,00 lbs/yr or use more than 10,000 lbs/hr of listed toxic chemicals must report annual releases to the environment .
Release Prevention and Control – SARA Title III
Release Prevention and Control
Prevention of Accidental Releases – Hazardous Substances Defined as:
Any chemical listed under Section 112(r) or any other chemical which may, as a result of short-term exposures, cause death, injury, or property damage due to their toxicity, reactivity, or corrosivity.
Release Prevention and Control
Prevention of Accidental Releases – Section 112(r) Risk Management Planning
Owners/operators of stationary sources subject to Section 112 (r) that use, store or process listed hazardous chemicals at or above designated thresholds must implement a Risk Management Program the includes -
An off-site consequence analysis to evaluate: A worst-case scenario and Other alternative release scenarios.
Develop and maintain a 5 year release history. A Release Prevention Program. An Emergency Response Plan
Release Prevention and Control
Prevention of Accidental Releases – Section 112(r) General Duty Clause
Owners/operators of stationary sources that produce, process, handle or store any listed substance or other extremely hazardous substance below the threshold quantity must develop and implement plans to –
Identify hazards which may result for releases using appropriate hazard assessment techniques.
Design and maintain a safe facility, taking steps as necessary to prevent releases, and
Minimize the consequences of accidental releases.
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