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VIII. Air Emissions

Source: EPA 1994 Toxics Release Inventory
Public Data Release, Appendix A:
Questions and Answers


Q60 What are the air quality impacts and toxicity concerns for the TRI chemicals with the largest air releases?

A The 15 chemicals with the largest releases to the air account for 79% of all air releases.

A number of TRI chemicals (e.g. methanol, toluene, xylenes, styrene) are volatile organic compounds (VOCs) that participate in atmospheric photochemical reactions that contribute to the secondary formation of tropospheric (ground-level) ozone, commonly referred to as smog. Ground-level ozone is a respiratory tract irritant that reacts rapidly with the tissues and fluids lining the airways of the lungs. Ozone is known to exacerbate pre-existing respiratory conditions such as asthma.

Additionally, a number of the chemicals reported to TRI that pose direct health effects are regulated under the Clean Air Act Amendments as Hazardous Air Pollutants (HAPs). The possible health effects are classified into several categories:

Carcinogenic: Chemicals that have a probability of resulting in cancer.

Reproductive: Chemicals that have a probability of causing adverse effects on the reproductive system.

Developmental: Chemicals that have a probability of causing detrimental effects during the embryonic stages of development.

Neurotoxicity: Chemicals that have a probability of causing adverse effects on the nervous system.

Q61 What regulatory authority does the Agency have to reduce toxic air emissions?

A Title I of the Clean Air Act Amendments (CAAA) covers emission reduction for volatile organic compounds (VOCs) to meet ambient air quality standards for ozone. These programs are controlled to some extent by state and/or local governments. A number of TRI chemicals are regulated under Title I as VOCs that participate in atmospheric photochemical reactions to produce ozone, a regulated ambient air pollutant.

Title III of the CAAA is the primary regulatory tool by which EPA controls emissions of air toxics. Title III (specifically section 112) lists 189 Hazardous Air Pollutants (HAPs), almost all of which are part of the TRI list. Twelve of the top 15 TRI chemicals with the largest air emissions are also HAPs.

Title III, section 112(b) of the CAAA, lists hazardous air pollutants (HAPs) that EPA is required to regulate by categories of HAPs sources. In accordance with section 112, EPA published the final list of categories of sources to be regulated on July 16, 1992 (57 F.R. 31576). Under section 112(d), EPA must issue regulations requiring listed categories of sources emitting HAPs to utilize control technologies to reduce their air emissions, for example, the maximum achievable control technology (MACT). After the application of the maximum achievable control technology (MACT) standards, section 112(f) states that EPA may issue additional standards, if necessary, within eight years to further protect the public.

One of the first standards to be promulgated under Title III was the Hazardous Organic National Emissions Standards for Hazardous Air Pollutants, or the HON Rule, October 1992. The HON Rule had far-reaching effects because it required reductions of 110 of the 189 hazardous air pollutants. The HON/MACT standard affected many sources of toxic emissions, such as process vents, equipment leaks, and storage tanks at chemical manufacturing plants. The requirement resulted in substantial reductions in emissions from the affected facilities.

Title III, Section 112(r) of the CAAA, requires EPA to develop risk management planning (RMP) regulations to help prevent accidental releases of at least 100 substances. In January 1994, EPA promulgated a final list consisting of 140 toxic and flammable substances, as well as Division 1.1 explosives, which will be subject to the requirements in the RMP rulemaking. Facilities producing, handling, or storing threshold quantities of listed substances, including chlorine and ammonia, will be required to undertake a risk management program and develop risk management plans available to the public. The program must include a hazard assessment, prevention program, and emergency response program.

In addition to the other air pollutant regulations, section 604 of Title VI mandates restrictions of ozone-depleting chemicals. On December 10, 1993, EPA published a final rule (58 FR 65018) that phases out the production of ozone-depleting chemicals, including Freon 113, dichlorodifluoromethane (CFC-12), and 1,1,1- trichloroethane (methyl chloroform), by January 1, 1996, due to their ozone-depleting potential. The effective date of this rule was January 1, 1994. (See question 49 for the ozone-depleting chemicals added to TRI.)

The EPA's Technology Transfer Network Bulletin Board System (TTN BBS) is an excellent resource for information regarding proposed and promulgated rules pursuant to the 1990 CAAA. The modem number is (919) 541-5742, and it operates at 8,N,1 (8 databits, No parity, 1 stopbit). For more information regarding the TTN BBS, including Internet access, contact the help desk at (919) 541-5384.

Q62 How are the TRI chemicals with large quantities of air emissions regulated?

A Listed below are the 10 chemicals with the greatest total reported air emissions in TRI for 1994, and the authority by which they will be regulated under the Clean Air Act Amendments.

Regulated Provision under
Chemical Clean Air Act Amendment

Methanol Title I and Title III Section 112(b)
Toluene Title I and Title III Section 112(b)
Ammonia Title III Section 112(r)
Xylene Title I and Title III Section 112(b)
Carbon disulfide Title I and Title III Section 112(b)
Methyl ethyl ketone Title I and Title III Section 112(b)
Hydrochloric acid Title III Section 112(b)
Dichloromethane Title III Section 112(b)
Chlorine Title III Section 112(b) and 112(r)
Glycol ethers Title III Section 112(b)
Styrene Title III Section 112(b)
1,1,1-Trichloroethane Title I, Title III Section 112(b), and Title VI
Ethylene Title I
Trichloroethylene Title III Section 112(b)
n-Butyl alcohol Title I

Q63 Why are some of the CAAA's 189 hazardous air pollutants (HAPS) not included in the TRI list of chemicals?

A Nine chemicals listed as HAPs in the CAAA that were not listed on EPCRA section 313 were proposed for addition as part of the Agency's expansion of the TRI chemical list. On November 22, 1994, EPA issued a final rule that added six of those nine chemicals to the TRI list. Facilities regulated under EPCRA section 313 were required to report on the following HAPs for the first time in reporting year 1995:

Dimethyl formamide
Hexamethylene-1,6-diisocyanate
Hexane
Phosphine
Polycyclic Organic Matter (polycyclic aromatic compounds)
Triethylamine

The following three HAPs were proposed for listing but deferred and as such are still not listed on EPCRA section 313:

Caprolactam
Isophorone
Mineral fibers

The following six HAPs have not been proposed for addition to the TRI chemical list:

Coke Oven Emissions
p,p'-Dichlorodiphenyldichloroethylene (DDE) Radionuclides (including radon)
2,3,7,8-Tetrachlorodibenzo-p-dioxin
2,2,4-Trimethylpentane

There are various reasons why the remaining hazardous air pollutants have not been proposed for addition to EPCRA section 313. Two examples follow: 1) Coke oven emissions is a process category. It consists of a mixture of various chemicals that are individually listed on EPCRA section 313 or are being proposed for addition to EPCRA section 313, i.e., polycyclic aromatic compounds. EPA believes that, for the purposes of the Toxics Release Inventory, coke oven emissions are more appropriately covered by listing the constituents rather than the process category. 2) Other chemicals such as 2,3,7,8-tetrachlorodibenzop -dioxin are not produced in quantities that will meet or exceed the EPCRA section 313 reporting thresholds. Listing this type of chemical would not result in the submission of TRI reports.

Source: USEPA 1994 Toxics Release Inventory Public Data Release (EPA 745-R-96-002, June 1996).

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