Collision Repair Training | United States
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Current Events/News: Advantage Online: 2005 Archives
RESPIRATOR END-OF-SERVICE LIFE INDICATORS (ESLI’s)
January 10, 2005 -Whenever working around hazardous chemicals in the repair facility, respirators should be worn. Failure to wear a respirator could eventually result in ill health effects such as respiratory irritation, increased colds, infections, and possibly cancer. Most respirators worn in a collision repair facility are the air-purifying type with replaceable cartridge filters (see Figure 1). These cartridges purify the contaminated air by absorbing harmful chemicals before the technician breathes the air. The unknown factor with cartridge respirators has always been knowing when the cartridge must be replaced? This is where “end-of-service life indicators,” or ESLI’s, come in. There are some respirator cartridges equipped with ESLI’s that provide a visible indicator that clearly shows when the cartridge is saturated and therefore, must be replaced. This might sound like a practical addition to every air-purifying respirator, but there are limitations on these indicators. For example, as of the publication of this article, there is no ESLI-equipped respirator that will detect automotive refinishing materials. ESLI’s are a continually evolving technology. Here is a brief history of respirator cartridge monitoring efforts. Respirator Change-Out Schedules Respirators used to be replaced only when “break-through” was detected. Break-through is when the user can taste or smell chemicals while the respirator is being used. This detection method is not safe because it is impossible to know the exact point at which any chemical actually breaks through. Depending on each person’s level of sensory capabilities and fatigue, chemicals may be sensed at different times by different people. Also, some chemicals do not have a taste or smell, such as isocyanates. Through the years and with federal legislation, it has become a requirement for repair facilities where respirators are used to have a respirator cartridge change-out schedule in place. This is basically a calendar that identifies a requirement to change respirator cartridges every two weeks, for example. A schedule is required for every employee that uses a respirator, and has to be documented in the respirator protection program for the repair facility. Knowing basically how long a specific respirator provides protection allows employees to replace the respirator cartridges before they stop offering the proper protection. But even with this method there are still many variables and unknowns. Though a written respirator change-out schedule is good, there are dynamic factors that may affect the life of a respirator filter. These factors include:
Although these factors may all be considered when establishing the change-out schedule, they are continually changing variables. To help ensure proper protection and avoid respirator cartridges from being used after their service life expires, respirator change-out schedules tend to error to the early side of the cartridge life expectancy. Many respirator makers such as NORTH, MSA, and 3M all have a complimentary online respirator change-out program. These programs can be located at: ESLI Eliminates Guesswork
ESLI’s help to eliminate the guesswork in determining when a respirator’s cartridges should be replaced. ESLI’s are indicators on the side of each filter cartridge that change color as the charcoal or other absorbent inside absorbs the chemicals (see Figure 2). The color change progresses from one end of the indicator window to the other. The service life of the filter is expired when the indication color fills the indicator window (see Figure 3). ESLI Limitations When using an ESLI, it is important to ensure that the chemicals you are being exposed to match the filter and ESLI you are using. There are ESLI-equipped cartridges available that will monitor cleaning chemicals such as ammonia and other vapors such as acid. Earlier, we mentioned that an ESLI has not yet been developed that effectively monitors cartridge life for automotive refinishing products. Note that there is an ELSI filter cartridge designed to protect against organic vapors for Toluene Diisocyanates (TDI), but TDI's are not the isocyanates used in automotive refinishing products. Those isocyanates are referred to as 1,6 Hexamethylene Diisocyanates (HDIs). Therefore, this ELSI-equipped cartridge would not detect the type of isocyanates used in automotive refinish products. Isocyanates receive a lot of attention when discussing hazardous materials, but the problem with the development of an effective ESLI for automotive refinishing materials is not the isocyanates. It is actually the solvents. There has not been an ESLI developed yet that effectively detects the solvents in automotive paints. Isocyanates will stick (adsorb) to the charcoal and will not release. The solvents, on the other hand, must be absorbed by the charcoal and will break through before the isocyanates once the cartridge reaches its saturation point. Therefore, when an air-purifying respirator is used while refinishing, a written respirator change-out program is required while using the cartridge that offers the proper protection. Different countries have varying regulations on respirator use. Canada currently does not allow air-purifying respirators to be worn in environments where refinishing materials are being applied. In the United States, the revised OSHA Respiratory Protection Standard does allow the use of an air-purifying respirator when applying finishes in a spraybooth, but only if the following two requirements are met:
Conclusion Respirator cartridges equipped with an ESLI will monitor their life for some contaminants, such as ammonia, but not for most uses in a collision repair facility. Therefore, a respirator change-out schedule is still required for most operations. More information on respirator change-out schedules is being written in a revision of the I-CAR Enhanced Delivery program Hazardous Materials, Personnel Safety, And Refinish Safety (WKR01). Watch for it soon in your area. |
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