Instead of a one-size-fits-all approach, an ESLI allows cartridge change-outs to occur based on each employee’s individual work hours, exposure levels, and breathing rates while also factoring in different environmental conditions. (3M Personal Safety Division photo)

Common Questions Safety Managers Ask About Using ESLIs for Organic Vapors

End-of-service-life indicators have the potential to help organizations minimize lost time, reduce workers' compensation costs, and help save on equipment costs.

Workers who wear cartridge-based respirators to keep protected from organic vapors have traditionally had only one method for determining when they should replace their cartridges: a change-out schedule.

The introduction of new respirator cartridges with end-of-service-life indicators (ESLIs) has changed that. Previously available only for specific gases, such as mercury vapor or carbon monoxide, cartridges with ESLI technology are now available for use with a broad range of organic vapors above certain concentrations. This gives many safety managers and industrial hygienists their first real choice for determining change-out timing.

It may seem like a minor development, but ESLIs offer potentially significant opportunities for organizations that want more options to reduce safety risks and better manage equipment costs.

OSHA standard 29 CFR 1910.134 permits the use of ESLIs as a primary method in certain instances for determining when to replace cartridges. However, a lack of familiarity with ESLIs may make some safety professionals hesitant to adopt them as an alternative to change-out schedules. To help improve understanding of ESLIs—including how they work, when they can be used, and how they can improve cartridge change-out programs—it is worth examining some of the most common questions about the technology.

Q: What is an ESLI, and how does the new organic vapor ESLI work?
A: An ESLI is indicator on a respirator cartridge that enables a worker to monitor his or her cartridge’s service life and identify when the cartridge needs to be replaced. This new ESLI absorbs organic vapors as they travel through the cartridge, which in certain environments results in a visible change on the ESLI's indicator bar. When appropriate as a primary change-out method, the worker knows it is time to replace his or her cartridge when the indicator bar reaches the end-of-service line.

Q: Why use an ESLI in place of a change-out schedule?
A: Even a change-out schedule that is based on a properly executed exposure assessment and uses the objective information required by OSHA can be subject to worker and environmental variances that impact its accuracy. Worker variances can include different breathing rates, work practices, and exposure durations, while environmental variances can include changes to a work site's temperature or relative humidity. Variations in any of these can impact cartridge service life.

An ESLI accounts for these variances. Instead of a one-size-fits-all approach, an ESLI allows cartridge change-outs to occur based on each employee's individual work hours, exposure levels, and breathing rates while also factoring in different environmental conditions.

As a result, an ESLI can help optimize respirator cartridge use to help ensure workers are not using cartridges beyond their service lives. This can reduce workers' potential exposure risks and give workers greater confidence in their own safety. In some cases, it can show that cartridges may be used longer than previously thought, which can help companies save on equipment costs.

Q: How do I know whether I can use this organic vapor ESLI as my primary method for determining cartridge change-outs?
A: This organic vapor ESLI can be used as the primary method for determining cartridge change-outs if the minimum indication level (MIL) for organic vapors is less than the occupational exposure limit and the exposures are greater than the MIL. Free tools that are available use information collected from a safety professional’s exposure assessment to determine whether an ESLI is an acceptable primary method.

Q: Can an ESLI be used as a complement, or in addition to, a change-out schedule?
A: Yes. Some organizations may choose to use an ESLI in addition to a change-out schedule to help reduce workers' potential exposure. For example, an ESLI can be used as a backup method to a change-out schedule when a work site experiences unexpected or irregular spikes in exposures.

In these instances, workers should change their cartridges based on either the change-out schedule's normally scheduled intervals or when the ESLI bar reaches the end-of-service line, whichever occurs first.

Q: Can this organic vapor ESLI handle a mixture of organic vapors or changes in environmental conditions?
A: This new organic vapor ESLI has been tested and validated for different organic vapors and mixtures. It can absorb a mixture of organic vapors together, which will likely increase the visible change on its indicator bar. However, it is still important that the ESLI be appropriate for the individual organic vapor in the mixture that has the shortest service life.

Relative humidity and temperature ranges found in most workplaces also will not affect this organic vapor ESLI's performance. In fact, the ESLI bar will reflect how these conditions affect the indicator's service life.

Q: Is the cartridge fully used up when the indicator bar reaches the end-of-service line?
A: No. The National Institute for Occupational Safety and Health (NIOSH) requires that an ESLI "must indicate sorbent depletion at less than or equal to 90 percent of the service life."1 This provides an additional safety measure for workers, letting them know that a cartridge must be replaced while at least 10 percent of the service life remains. There could be significantly more remaining service life in certain environmental conditions and with certain organic vapors, but the cartridge always should be discarded as soon as the ESLI bar reaches the end-of-service line to ensure worker safety.

ESLIs offer a more worker-focused approach to cartridge change-outs. More than that, they have the potential to help organizations enhance safety and at extremes to minimize lost time, reduce workers' compensation costs due to organic vapor exposures, and help save on equipment costs.


This article originally appeared in the February 2016 issue of Occupational Health & Safety.

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