As stated in the Federal Register, effective December 30, 2013, the “All Appropriate Inquiry Rule,” found at 40 CFR Part 312.11 was amended to add as paragraph (c)- a reference to ASTM International’s E1527-13 “Standard Practice for Environmental Site Assessments: Phase I Environmental Site Assessment Process.”  ASTM E1527-13 was included to “make clear that persons conducting all appropriate inquires may use the procedures included in this standard to comply with the All Appropriate Inquires Rule.”  Now both ASTM E1527-05 and E1527-13 have been found by the EPA to comply with the due diligence requirement.  Commentators agree that  ATM E1527-13 is more stringent and requires consideration of Vapor Intrusions (indoor air quality) related to hazardous substances or petroleum products , broadens the consideration of prior remediations and  changes how prior releases may be characterized.  Purchasers and Lenders would be expected to require compliance with the ASTM E1527-13 standard.