APENs and air permits Determine if you need to submit an APEN, download APENs, apply for or modify a permit. Compliance and enforcement Fulfill permit requirements, access recordkeeping forms and guidance, download malfunction reporting form. Title V operating permits For sources in our Title V program (large sources). Emission reduction credits (ERC) Apply for, use, or change ownership of ERCs. Air Quality Modeling Guidance for Permits Determine if your project requires a dispersion modeling analysis to show compliance with the NAAQS.