GAS Inc. is requesting a change to one of the test methods, ASTM D6348-03. The change being requested will be used to check detector linearity of the Fourier Transform Infrared (FTIR) instrumentation used to conduct this method.

We (EPA) believe that this alternative is acceptable for use for use in testing all engines subject to 40 CFR part 60 Subpart JJJJ and 40 CFR part 63, Subpart ZZZZ. Also, we will post this letter as ALT-141 on EPA’s website (at to announce that our approval of this alternative test method is broadly applicable to engines for the purposes of meeting Subparts JJJJ and ZZZZ.

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