Overview of Air Pollutants and Management Strategies – Env 247 – February 24, 2011

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)

EXAMPLE OF MODEL RESULTS

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.