End-of-Service Life Indicator (ESLI)

DESCRIPTION provided by applicant Industrial workers must be able to function in environments where chemical hazards are present Thus they need protection against hazardous chemicals used in the workplace Particularly relevant is the use of respiratory protection for environments where workers are exposed to chemical vapors gases In most cases respiratory protection consists of a respirator face mask that is equipped with replaceable filter beds known as cartridges For these types of respirator masks once a cartridgeandapos s capacity for adsorbing chemicals is used up the expired cartridge can simply be thrown away and replaced with a fresh unused cartridge Unfortunately there is no reliable way to determine when the filter cartridge has expired thus the wearer is often exposed to the vapors after the cartridge is saturated but before it is replaced An OSHA standard for respirator cartridge use requires that employers provide either a rigorous change out schedule or use a National Institute of Occupational Safety and Health NIOSH certified end of service life indicator ESLI to determine when a respirator cartridge needs to be replaced Because no reliable certified commercially available ESLI has been developed employers rely on respirator change out schedules These schedules however are often inaccurate and unreliable because the input parameters used to calculate the lifetime of the cartridges are rarely accurately known As a result wearers of the mask often do not follow the change out schedules and are frequently exposed to chemical vapors prior to changing respirator cartridges Further the Bureau of Labor Statistics and NIOSH surveys show that some of all the workers determine their own respirator change out schedules which is against OSHA regulations An effective NIOSH approved ESLI technology that warns the user of impending contaminant breakthrough would provide an unambiguous means of safely determining when a respirator cartridge should be replaced To date however there is no commercial ESLI technology for respirator cartridges that responds to the types of contaminants that are prevalent in common industrial environments Should this technology be available in respirator cartridges not only would an ESLI prevent the harm to workers that is caused by incidental overexposure to vapors but it would be attractive to employers because it would eliminate the added expenses incurred from unnecessary replacement of partially used cartridges resulting from conservative change out schedules In summary an effective ESLI technology would improve the safety of the more than million annual respirator cartridge users in the U S and it would be adopted because it saved money an effective but expensive system would do little to improve safety because few companies would use it In the Phase I project TDA has developed and demonstrated a colorimetric ESLI that changes color in response to organic vapors acid gases and basic gases In the Phase II proposal TDA proposes to further develop the end of service life indicator ESLI and incorporate it into prototype respirator cartridges with the help of our collaborators PUBLIC HEALTH RELEVANCE No simple technology has yet been developed that allows the user of a respirator to determine if the chemical protection capability of its respirator filter cartridge has been reduced by exposure during storage or by saturation with gases while it is in use As a result many workers who are required to use respirator protection are at risk for chemical exposure because the filter cartridge change out schedules are not reliable surveys show that up to of the users simply change their cartridge when they smell a breakthrough In this proposal TDA proposes to further develop an end of service life indicator ESLI that visually signals the wearer that a respirator filter cartridge is about to expire thus unambiguously providing a safe reliable means of determining that a respirator filter cartridge is at the end of its service life and needs to be replaced