Knowing the specific contaminant and exposure levels is important to determine the appropriate respirator and cartridge for your work environment. This information will also help in estimating the life of selected 3M™ Cartridges. 3M™ Organic Vapor Monitor 3500+ uses diffusion, rather than a pump, to collect an air sample with an accuracy of +/-25%, at a 95% confidence level for many workplace organic vapors, for both personal or area sampling. It contains a single charcoal sorbent wafer for easy collection of organic vapors and can be used for most applications. After following all instructions, send the monitor to be analyzed in the lab of your choice. This monitor has a 2-year shelf life from its production date.