July 2, 2001

Kathryn A. Watson, Chief
Air Programs Branch
Office of Air Quality Indiana Department of Environmental Management
P.O. Box 6015
Indianapolis, Indiana 46206-6015

Re: Clarification of SPI's Position on Use of Emission Factors

Dear Ms. Watson:

In March 2001, The Society of the Plastics Industry, Inc. (SPI) submitted comments on the Indiana Department of Environmental Management's (IDEM's) proposed amendments to its emission reporting rule. 24 Ind. Reg. 1462 (Feb. 1, 2001). In discussing these comments at a subsequent SPI meeting, we realized that the comments could be misapplied outside the specific rulemaking addressed by the comments. In particular, SPI's comments could be misread as objecting to the use of emissions factors generally. Since SPI and its members have worked diligently to develop emission factors for various segments of the plastics industry, we are writing to clarify our support for the use of properly derived emission factors as a sound method for estimating actual emission levels.

As the voice of the plastics industry, SPI has long supported using emission factors as a cost effective, accurate method of calculating actual emission levels from permitted facilities. SPI has contributed extensively to the development of emission factors for the plastics industry. For example, the June 1996 issue of the Journal of the Air & Waste Management Association carried an article on SPI-sponsored research to develop emission factors for polyethylene processing. Similar SPI studies have developed emission factors for polypropylene processing, ethylene-vinyl acetate, and ethylene-methyl acryl ate copolymer processing. A list of studies is attached. The US Environmental Protection Agency has formally adopted some of the industry's work, such as emission factors for the reinforced plastics industry. See, http://www.epa.gov/ttnchie1/efdocs/cfa_rpt3.pdf

We are encouraged by IDEM's April 12, 2001, response to our comments in which IDEM expressed its commitment to consider how emission factors can be best used. We suggest that some of the criteria used by SPI in developing emission estimations are broadly applicable. Among other considerations, SPI-sponsored work employed US EPA protocols and reported the study results in enough detail that processors or others using the emissions factors could determine whether the study reflected a facility's specific operations. In addition, we have endeavored to have the emissions studies published in recognized journals.

We have a continuing concern with any requirement that IDEM 'approve' an emission factor before it is used by a facility. We recognize Indiana's authority to question the basis of any facility's filing or emission calculation. But, emission factors derived from well-conducted studies whose results are published by peer-reviewed journals or government agencies should be accepted. Under existing regulatory requirements, each facility is obligated to estimate its emissions based on the best-available data. Where emission factors are the best-available data, requiring their pre-approval by Indiana could hinder the calculation of the most current and accurate emission estimates and create inconsistencies in state and federal emission data sets.

Thank you for the opportunity to clarify our position on emission factors. SPI remains available to discuss this letter or to respond to any questions you may have on this issue. In the meantime, please do not hesitate to call if we can be of assistance in any way.

Respectfully submitted,

Maureen Healey

Back to Top

More Public Policy:  Environment . Worker Safety . Transportation . Codes and Standards . Food, Drug,and Cosmetic Packaging . International Trade . Other Issues