Knowing the specific contaminant and exposure levels is important to determine the appropriate respirator and cartridge for your work environment. 3M™ Ethylene Oxide Monitor 3551+ uses diffusion, rather than a pump, to collect an air sample with an accuracy of +/-25% at a 95% confidence level. It has a single treated charcoal sorbent wafer for easy collection of ethylene oxide and is typically used in pharmaceutical, health care and chemical industries. After following all instructions, send the monitor to be analyzed in the lab of your choice. This monitor has a 1-year shelf life from its production date.