Ethylene Oxide Monitor 3550 with Prepaid Analysis utilizes brominated carbon to collect and convert the reactive ethylene oxide to a more stable chemical derivative called 2-bromoethanol. This compound is then desorbed with methylene chloride in methanol. It meets OSHA requirement for accuracy within +/-25% for an 8-hour samplings at 1 ppm and the requirement for accuracy within +/-35% for 8-hour samplings at the 0.5 ppm action limit. These compact monitors clip easily to shirt lapel, collar, or pocket and don't interfere with employee activities. Monitors collect certain organic vapour type airborne contaminants using the scientific principle of diffusion. A sorbent pad in the base collects and holds the organic gases and vapours until desorbed for analysis in a laboratory. Monitors with Prepaid Analysis can be mailed unit to the 3M-approved labratory listed on the package for analysis. Monitors have an 18-month shelf life.