BOARD MEETING DATE: September 11, 2009
AGENDA NO. 31

PROPOSAL:

Amend Rule 102 – Definition of Terms

SYNOPSIS:

The proposed amendment adds several compounds to the list of exempt compounds in Rule 102. The U.S EPA has delisted these compounds from its definition of VOC because of their negligible photochemical reactivity.

COMMITTEE:

Stationary Source, July 24, 2009, Reviewed

RECOMMENDED ACTIONS:

Adopt the attached resolution:

1. Certifying the CEQA Final Environmental Assessment for the proposed amendment.
2. Amending Rule 102 – Definition of Terms.
    

Barry R. Wallerstein, D.Env.
Executive Officer

Background

The U.S. EPA revises the definition of VOCs for purposes of preparing State Implementation Plans (SIPs) to attain national ambient air quality standards for ozone under the Clean Air Act. The U.S. EPA lists chemical compounds that are excluded from the federal VOC definition based on the compound’s negligible contribution to the formation of tropospheric ozone (commonly known as smog). Smog is formed when VOCs react photochemically with nitrogen oxides in the atmosphere. EPA’s policy has been to exclude organic compounds with negligible reactivity level from the regulatory definition of VOCs, which helps states focus emission control efforts on VOCs that significantly increase ozone concentrations.

In determining negligible reactivity, the U.S. EPA compares the reactivity of a given organic compound to that of ethane. Compounds with reactivity levels lower than, or equal to, ethane under the assumed conditions may be deemed negligibly reactive, while compounds that are more reactive than ethane continue to be considered reactive VOCs, and therefore subject to control requirements.

During the past years, the U.S. EPA has revised the federal definition of VOCs to exclude several organic compounds with negligible photochemical reactivity. In November 2004, the U.S. EPA delisted methyl formate in response to a petition from Foam Supplies, Inc. to exclude the compound from the definition of VOC based on its lower reactivity rate than ethane. Besides having negligible reactivity, methyl formate has other desirable properties in that it has negligible ozone depleting potential (ODP) and a very low or zero global warming potential (GWP).

Effective February 2009, two additional organic compounds were added to the list of VOC exempt compounds, i.e., dimethyl carbonate and propylene carbonate, on the basis that these compounds are less photochemically reactive than ethane and, thus, have negligible contribution to tropospheric ozone formation. Kowa American Corporation petitioned the U.S. EPA seeking an exemption for dimethyl carbonate from the regulatory definition of VOC, while Huntsman Corporation submitted the exemption petition for propylene carbonate. Dimethyl carbonate and propylene carbonate are not classified as ozone depleting substances.

Exempting these three compounds from the VOC definition will provide product formulators and end users with added compliance flexibility in formulating and using new compliant products such as adhesives, coatings, ink, solvents, foam blowing agents and others. While compliance flexibility, low photochemical reactivity and overall lower ozone depletion and global warming potential are all positive attributes associated with these products, it is also equally important to assure that these compounds are safe to use and do not cause any undue risk to the workers, end users, and consumers utilizing products containing these compounds. Therefore, staff also considered the potential health effects in evaluating these compounds for exemption.
 

Public Process

During the development of Proposed Amended Rule 102, staff worked with industry and other persons affected by the proposed amendment. A public workshop was held on July 9, 2009. Comments received during the public workshop, including staff’s responses, are summarized in the Final Staff Report.
 

Proposal

Staff is proposing to add methyl formate, dimethyl carbonate, and propylene carbonate to the list of Group I exempt compounds in Rule 102. A VOC-exempt methyl formate may potentially reduce VOC emissions by approximately 238 tons per year or about 0.65 tons per day just from foam manufacturing operations. In addition, the use of methyl formate as replacement for some global warming VOC-exempt compounds would potentially reduce greenhouse gas emissions by about 171 tons per year or 0.47 tons per day.

For dimethyl carbonate and propylene carbonate, the emissions impact of exempting these compounds is difficult to quantify at this time due to a high degree of uncertainty in determining their potential penetration as replacement solvent in coatings and other formulation.
 

Key Issues

Key concerns and staff responses received during the rule development process are summarized below.

Issue: A study on dimethyl carbonate indicates that the chemical compound causes developmental toxicity in mice exposed by inhalation. The AQMD should delay the exemption for dimethyl carbonate until OEHHA performs toxicity evaluation of the compound.

Response: In formulating a recommendation to exempt a particular compound from the VOC definition, staff evaluates the potential health effects and any trade-offs very carefully to ensure that the proposed action would not cause any undue health risk to the workers, end users and consumers. This evaluation includes the review of existing literature, utilization of risk models available and soliciting input from sister agencies, such as CARB and OEHHA. Staff is aware of one teratology study that indicates certain developmental effects on mice exposed by inhalation to very high concentration (3,000 ppm) of dimethyl carbonate during gestation. However, the study found no effects for developmental toxicity at 1,000 ppm or 300 ppm exposure levels. Given the manufacturer’s recommended exposure level of 200 ppm and established exposure controls and personnel protection, staff believes that workers and the general public would not be subjected to undue risk at the expected level of exposure to dimethyl carbonate.

As part of this rule development effort, staff solicited OEHHA’s input on dimethyl carbonate, and has recently received feedback on a draft interim acute Reference Exposure Level (REL) developed by OEHHA staff, which has not undergone the public and peer review process. However, OEHHA did not provide any guidance on chronic risks in the absence of long term studies. Staff has conducted a risk screening utilizing the draft interim REL and found no exposures above the draft REL in various use scenarios. Furthermore, in the absence of final RELS from OEHHA and in an effort to further evaluate potential health impacts, AQMD staff conducted a health risk assessment for dimethyl carbonate using the screening level for methanol, which is the primary metabolite of dimethyl carbonate. This methodology is similar to OEHHA’s approach of assessing the effects of the known metabolites of a substance during its evaluation of the health effects from exposure to tertiary butyl acetate. More specifically, staff evaluated several very conservative scenarios to model risks based on methanol’s acute and chronic risk factors and found no significant risks from uses of dimethyl carbonate at small and larger facilities, as well as area source and consumer uses. The tables below summarize the results of the scenarios modeled.
 

Table 1 – Methanol Health Risk from Usage at Permitted Facilities (commercial/industrial)

Tier I – Health Risk Evaluation of Dimethyl Carbonate as Degradation Product

Table 2 – Methanol Health Risk from Non-Permitted Fugitive Use (residential/architectural coatings)

Tier I - Health Risk Evaluation of Dimethyl Carbonate as the Degradation Product Methanol

ª SCAQMD, Risk Assessment Procedures for Rules 1401 and 212, Package L, July 2008.

Dimethyl Carbonate (DMC) Emissions, lb/yr = DMC Usage, gal/yr x DMC Density, lb/gal

Methanol equivalent (MeOHeq) Emissions, lb/yr = DMC Emissions, lb/yr x DMC to MeOH conversion

MeOHeq Emissions, lb/hr = (MeOH Emissions, lb/yr)/(260 day/year)/(8 hour/day)

MeOHeq Emissions, lb/yr = MeOH emissions x 14 days/year

Based on this assessment, AQMD staff has concluded that there are no significant adverse impacts associated with exempting dimethyl carbonate as a VOC. Should future studies or feedback from OEHHA reveal any new information that might alter staff’s conclusions, staff will be prepared to expeditiously initiate a rule amendment to reflect the new information.

Issue: AQMD staff needs to re-evaluate tertiary butyl acetate (TBAc) for inclusion in the list of VOC exempt compounds in Rule 102. New toxicological data is available on TBAc that will address health concerns previously raised by OEHHA.

Response: Staff has previously analyzed the risks from TBAc’s primary metabolite, Tertiary Butanol, and determined that the risks may exceed threshold levels. Therefore, the AQMD has carefully carved out exemptions only in areas where the use of personal protective equipment is widespread, such as automotive refinishing and industrial maintenance coatings. Based on recent feedback from OEHHA staff, they still have concerns with the increased use of TBAc. Therefore, staff is not ready to propose TBAc for an exemption at this point. However, staff has committed to meet with CARB, OEHHA, and the manufacturer to continue discussions on the latest health studies presented by the manufacturer, and plans to follow OEHHA’s guidance in the future and propose another amendment to Rule 102, if necessary.
 

California Environmental Quality Act

Pursuant to the California Environmental Quality Act and AQMD Rule 110, a Draft Environmental Assessment (EA) was prepared for PAR 102 and was circulated for a 30 day public review and comment period from July 28, 2009 to August 26, 2009. Responses to any comments on the Draft EA received during the public review and comment period will be prepared and incorporated into the Final EA.
 

Socioeconomic Assessment

There is no additional cost to users of the three compounds proposed for exemption since use of these compounds is strictly voluntary. However, PAR 102 allows flexibility by providing additional options in meeting AQMD’s strict VOC requirements. Furthermore, PAR 102 would lower emission fees for facilities and manufacturers opting to use any of these proposed exempt compounds.

In conclusion, PAR 102 would result in savings to the affected facilities, and therefore, would not have any adverse socioeconomic impacts.
 

AQMP and Legal Mandates

The California Health and Safety Code requires the AQMD to adopt an Air Quality Management Plan to meet state and federal ambient air quality standards in the Basin. In addition, the California Health and Safety Code requires that the AQMD adopt rules and regulations that carry out the objectives of the AQMP.

The proposed amendment to Rule 102 helps reduce VOC emissions by providing additional options in meeting AQMD’s VOC limits, and supports AQMD’s air quality objective of achieving state and federal air quality standards.
 

Implementation and Resources

Current AQMD resources are sufficient to implement the proposed amendments with no additional fiscal impact.
 

Attachments (EXE, 1.8m)

1. Summary of Proposal
2. Rule Development Process
3. Key Contacts
4. Resolution
5. Proposed Amended Rule 102 Language
6. Final Staff Report
7. Final Environmental Assessment