During the initial years after the enactment of the Clean Air Act (CAA), the information required by the Act, which included concentrations, purpose, and chemical composition, was submitted using a single form. The Act was amended over the next two decades to include required testing of registered Fuel and Fuel Additives (F/FA) as well as testing for effects of potential emissions on public health and welfare.

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Post-1994 Data Requirements for 211(b)

Tier 1 Tier 2 Tier 3
Tier 1 required manufacturers to submit:
  • a literature search for available information on the composition and effects of F/FA emissions on public health and welfare;
  • a chemical analysis to characterize the emissions of fuels or additive/base fuel mixtures; and
  • a qualitative discussion of potential exposures of the particular fuel(s) or additive/base fuel mixture(s).
The Tier 2 testing framework in the 1994 rule consisted of:
  • a 90-day subchronic mammalian inhalation study to examine general systemic and organ toxicity (including pulmonary effects), with the addition of ancillary tests that allow the assessment of several specific health effect endpoints (carcinogenicity, mutagenicity, teratogenicity, reproductive toxicity, and neurotoxicity) within the same exposure schedule.
  • A fertility assessment coordinated with the 90-day study to examine reproductive and teratogenic effects.

EPA could allow an Alternative Tier 2 test program when indicated by the results of Tier 1.

On the basis of the Tier 1 and/or Tier 2 data, or any other available information:
  • EPA will determine whether further testing and/or analysis for the subject fuel or fuel additive is needed under the provisions of Tier 3.
  • Given the variety of evaluations included in Tiers 1 and 2 and the wide range of possible interrelated outcomes which could be obtained, EPA proposed to use its discretion in determining the need for Tier 3 testing on a case-by-case basis.

The latest requirements for Registration of Fuels and Fuel Additives can be found in 40 CFR Part 79 at

The EPA Office of Transportation and Air Quality has additional information on Fuel and Fuel Additive Registration at