The following links provide site screening guidance and tools for in the determining whether diffusion sampling might be appropriate for a given application:
User's Guide for Polyethylene-Based Passive Diffusion Bag Samplers to Obtain Volatile Organic Compound Concentrations in Wells (Part I, Part II) - guidelines and recommendations on the use of diffusion samplers including site characteristics suitable for their use (Vroblesky, D.A., 2001a).