Rule R307-121 has been amended five times since the last five-year review: DAR No. 35718 (nonsubstantive change), DAR No. 36809 (nonsubstantive change), DAR No. 37990 (effective 01/01/2014), DAR No. 38837 (effective 01/01/2015), and DAR No. 39353 (effective 09/03/2015). One comment was received in relation to changes made to DAR No. 38837. The comment was about concerns that the proposed rule did not require any evidence that the system meets state emission requirements or is safe according to NFPA 52 code. Instead it puts the responsibility on the taxpayer to know those requirements and to certify that the installation complies with them. Division of Air Quality (DAQ) Response: The person commenting is correct when stating that the responsibility to ensure that the system meets emission and safety requirements falls on the taxpayer. Subsection 19-2-406(1) states that the owner of the converted vehicle is responsible to ensure that the vehicle is inspected by a CSA America Inspector and tested to ensure that the vehicle satisfies emission standards. No other comments have been received since the last five-year review.