Decontamination reagents for CWAs and TICs may be grouped into the following two broad categories:
- Surface-applied Reagents. Surface-applied reagents that utilize various reaction chemistries may be effective on some nonporous surfaces but may corrode or degrade the surface. Surface applied reagents are further broken down into:
- Solid and Liquid Reagents. Decontamination solutions may pool on horizontal surfaces for a longer time than other surfaces.
- Foam and Gel Reagents. Foams and gels use less decontamination reagent and maintain longer contact time with surfaces but may present more cleanup problems. Foams and gels have varying effectiveness on vertical and overhead surfaces
- Vapor and Gas Reagents. Vapors and gases have been demonstrated to be effective against biological contamination in enclosed spaces, but there are fewer data available indicating effectiveness in decontamination of chemicals. Both vapors and gasses might be effective in decontamination of residual subsurface CWAs; studies of this application are ongoing.
CWA or TIC permeation into materials may also impact decontamination effectiveness. Permeation varies by material (e.g., porous, nonporous, organic, polymeric) and also by the contamination scenario (e.g., vapor and/or aerosol condensation and minor spill versus heavy splash). Most decontamination reagents are more effective on the surface of contaminated objects and have limited ability to destroy CWAs/TICs that have permeated a material, but vapors near the surface might be destroyed while the decontamination reagent is present. However, after removal of the decontamination reagent, permeated CWAs/TICs will continue to slowly leach out and pose a hazard unless the hazardous chemical is destroyed within the porous material.
No single decontamination reagent or method is applicable in all situations. EPA’s HSRP has summarized currently available decontamination products and technologies that have shown various levels of efficacy for TICs and CWAs that may impact a variety of surfaces, large volumetric spaces, and sensitive items such as electronics. No summary is exhaustive and no recommendation of these products by the EPA is implied. Other decontamination products using mechanical/physical or monitored natural attenuation procedures can also be used. A cost versus efficacy assessment should be done in addition to a technical feasibility study to determine if the technology or procedures selected meet the clearance decisions in a timely, cost-effective manner.