On September 13, 2016, governors of seven ethanol producing states wrote to EPA Administrator Gina McCarthy requesting the removal of the Reid Vapor Pressure (RVP) limit on E15. RVP measures gasoline volatility, and E10 receives a one pound-force per square inch (psi) RVP waiver between June 1 and September 15 that is not extended to E15. The letter states "EPA's disparate handling of E10 and E15 with regard to fuel volatility regulation is stifling the widespread adoption of E15 and mid-level ethanol blends." The governors continue to argue that "This inequitable RVP treatment of E10 and E15 has no scientific basis since E15 and higher blends are lower in volatility than E10 when blended with the same base gasoline. We strongly urge you to take immediate action to establish a volatility regime that allows a uniform gasoline blendstock to be suitable for blending both E10 and E15 (and higher blends) year round." The American Coalition for Ethanol and the Iowa Renewable Fuels Association have both spoken out in support of the letter, stating the RVP limit is one of many barriers to ethanol being competitive in the fuel market.