Evaluation of activated carbon respirator filter effectiveness by concentration mapping of dimethyl methylphosphonate

Activated carbon (AC) has been used extensively in personal protective equipment (PPE) to adsorb toxic substances for the purpose of protecting the user from exposure. The ability to evaluate localized carbon utilization in multiple PPE designs would help engineers develop more effective PPE. Therefore, a method to map dimethyl methylphosphonate (DMMP), a common PPE testing agent, concentrations throughout AC filters was developed and tested on DMMP-exposed filters, some purposefully occluded to simulate defective filters. DMMP concentrations were highest at the point of entry and dispersed outward in a radial pattern from that site, decreasing with distance from the point of exposure. Occluded filters were detected by observing DMMP adsorption inconsistent with unblocked filters and showed high concentrations of DMMP localized in unblocked areas of the filter. The DMMP mapping technique detailed in this study provides a tool for testing AC utilization inside DMMP-exposed PPE.