American Society of Testing and Materials (ASTM) established the following two standards or practices for Environmental Site Assessments (ESA) in commercial real estate transactions to standardize "Environmental Due Diligence":

• ASTM E 1527 Phase I Environmental Site Assessment (Phase I ESA) - To identify any environmental conditions or problems in connection with the property due to presence of hazardous materials. Phase I ESA serves as protection against purchasing or financing a property with known or potential environmental liabilities. The Phase I ESA consists of the following four components:

1- Site visit
2- Review of public records / State regulatory database information
3- Interviews with the current and past owners and/or occupants
4- Historical aerial photographs


• ASTM E 1528 Transaction Screen - This standard practice consists of a questionnaire and a corresponding guide. The Transaction Screen consists of the following three components:

1- Site visit
2- Limited review of public records / Historical land use research
3- Interviews with the current and past owners and/or occupants


• ASTM Phase II Environmental Site Assessment - Phase I environmental site assessments do not address every environmental concern that could be encountered, therefore Phase II study is required. The purpose of the Phase II investigations is to estimate the nature and extent of contamination and to provide the basis for a preliminary assessment of the cost for corrective or preventive action.