This chapter describes requirements for accreditation and certification of environmental testing laboratories. Accreditation is voluntary; however, the commission may accept environmental testing laboratory data and analyses for use in commission decisions regarding any matter under the commission's jurisdiction relating to permits or other authorizations, compliance matters, enforcement actions, or corrective actions only if the data and analyses are prepared by an environmental testing laboratory accredited by the commission under this chapter, except as provided in §25.6 of this title (relating to Conditions Under Which the Commission May Accept Analytical Data).