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DOW CHEMICAL U.S.A. February 18, 1982 Bill Herrick LHC III Building 6801 cc: Woody Chew, 6801 Charlie Halphen, 3502-E John Holloway, 6801 Terry Whitman, 6801 icuis.ava division P. O. BO> ifeO PlAOUEMINE, LOUISIANA 70764 604 8000 RESPIRATOR CARTRIDGE SHELF LIFE In response to your recent inquiry on frequency of replacing cartridges in unused respirators, I have summarized below the results of a study done by the U.S. Area Industrial Hygiene Laboratory. Several half-mask respirators with new cartridges were stored in a variety of atmospheres to determine the effect of humidity and background chemical contamination on the service life of the cartriiages. At intervals of *1,6,10 and 12 months, one of the respirators was withdrawn from each group and tested for time to breakthrough. The test used was essentially the same one used by IJIOSH for certification of commercial cartridges. A test atmosphere of 1000 ppm CClij is pulled through the cartridge and the purified air is monitored until it reaches a level of 5 ppm. To pass the test, a cartridge must last at least 50 minutes. The test conditions are summarized below along with the service life test results. Group #1: 55# relative humidity, 23C Group #2: 85# relative humidity, 23C Group #3: Group irA: Same as #1 plus 150 ppm Chlorothene exposure 6 hr/day 5 days/week Same as ft3 but using 500 ppm Chlorothene Group #5-' Stored in production plant, 20 - 70a relative humi dity, 5 - 30C, background approximately 30 ppm methyl chloride. Test Results A months: 6 months: 10 months 12 months All groups passed. All groups passed. Group ft2 failed, others passed. Groups ft 2 and it A failed, others passed. AN OPERATING UNIT OF THE DOW CHEMICAL COMPANY DO 078713 OONFTDFNTTAI fI ( 2- - Based on this data, I see no reason to discard any cartridges in less than six months. If the respirators are kept in sealed plastic bags to protect them from the high humidity, they would probably be good for up to a year. In the tests described above, the cartridges were left exposed to the atmosphere. If you have any further questions, don't hesitate to contact me. Bill Ledford Industrial Hygiene sb s 00 078214 OONFTDFNTTAI.