Abstract
Passive dosimeters with instant readout capability have been devised by combining the principles of a gas indicator tube with membrane control of mass transfer. The membrane controls the diffusion of the gas or vapor to the reagent impregnated support where it reacts to produce a stain. Results with H2S and benzene monitors demonstrate that time weighted average concentration of ambient gas or vapor can be measured accurately and precisely by following the movement of the colored stain in the specially prepared and calibrated indicator tube. The 95% confidence interval of such measurements at the TLV (80 ppm-hrs) is ±20% for H2S and ±15% for benzene, well within NIOSH limits of acceptability.