A Comparison of the OSHA Modified NIOSH Physical and Chemical Analytical Method (P and CAM) 304 and the Dust Trak Photometric Aerosol Sampler for 0-Chlorobenzylidine Malonitrile
Uniformed Services University Of The Health Sciences Bethesda United States
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The U.S. Army uses riot control agent o-chlorobenzylidene malononitrile CS for conducting mask confidence chamber training, which all U.S. Army recruits must complete. The effects of CS include paintearing of the eyes, upper respiratory track irritation, nasal irritationdischarge, salivation and burning of the skin. These effects are experienced by recruits as required tasks are completed breaking the seal and completely removing the mask. Airborne and particulate CS levels are currently not measured with a real time monitor inside the mask confidence chamber. This study compared the nonspecific, rapid photometric particle counting instrument, DustTrak, to the established OSHA modified NIOSH P and CAM 304 method to determine correlation between the two methods. Results were compared using paired t-test, correlation coefficient, and Bland-Altman limits of agreement. While the methods were found to be comparable p0.05, they showed weak positive association r 0.03. Additionally, the statistical comparison identified limits of agreement with large ranges about the mean -29.7 to 20.5 mgm filter and -13.1 to 13.3 mgm filtertube relative to established occupational health limits and guidelines. Given the ACGIH-TLV of 0.39 mgm, and IDLH is 2mgm3, the limits of agreement suggest that the use of the DustTrak direct reading instrument to characterize CS concentrations during mask confidence chamber training may not be a reliable approach when attempting to provide an accurate characterization and reasonable margin of safety for human health. While not well correlated to the established, laboratory accepted standard for determining airborne CS concentration, the DustTrak instrument may potentially be well-suited to non-specific dusty environments.