| The Use of Respirators is the Least
-- Respirators should be used for protection only when engineering controls have been shown to be infeasible for the control of the hazard or during the interim period when engineering controls are being installed.
Engineering and work practice controls are generally regarded as the most effective methods to control exposures to airborne hazardous substances. OSHA considers the use of respirators to be the least satisfactory approach to exposure control because…
Appendix B-2 to § 1910.134: Respirator Cleaning Procedures (Mandatory)
These procedures are provided for employer use when cleaning respirators. They are general in nature, and the employer as an alternative may use the cleaning recommendations provided by the manufacturer of the respirators used by their employees, provided such procedures are as effective as those listed here in Appendix B- 2. Equivalent effectiveness simply means that the procedures used must accomplish the objectives set forth in Appendix B-2, i.e., must ensure that the respirator is properly cleaned and disinfected in a manner that prevents damage to the respirator and does not cause harm to the user.
I. Procedures for Cleaning Respirators
A. Remove filters, cartridges, or canisters. Disassemble facepieces by removing speaking diaphragms, demand and pressure- demand valve assemblies, hoses, or any components recommended by the manufacturer. Discard or repair any defective parts.
B. Wash components in warm (43 deg. C [110 deg. F] maximum) water with a mild detergent or with a cleaner recommended by the manufacturer. A stiff bristle (not wire) brush may be used to facilitate the removal of dirt.
C. Rinse components thoroughly in clean, warm (43 deg. C [110 deg. F] maximum), preferably running water. Drain.
D. When the cleaner used does not contain a disinfecting agent, respirator components should be immersed for two minutes in one of the following:
1. Hypochlorite solution (50 ppm of chlorine) made by adding approximately one milliliter of laundry bleach to one liter of water at 43 deg. C (110 deg. F); or,
2. Aqueous solution of iodine (50 ppm iodine) made by adding approximately 0.8 milliliters of tincture of iodine (6-8 grams ammonium and/or potassium iodide/100 cc of 45% alcohol) to one liter of water at 43 deg. C (110 deg. F); or,
3. Other commercially available cleansers of equivalent disinfectant quality when used as directed, if their use is recommended or approved by the respirator manufacturer.
E. Rinse components thoroughly in clean, warm (43 deg. C [110 deg. F] maximum), preferably running water. Drain. The importance of thorough rinsing cannot be overemphasized. Detergents or disinfectants that dry on facepieces may result in dermatitis. In addition, some disinfectants may cause deterioration of rubber or corrosion of metal parts if not completely removed.
F. Components should be hand-dried with a clean lint-free cloth or air-dried.
G. Reassemble facepiece, replacing filters, cartridges, and canisters where necessary.
H. Test the respirator to ensure that all components work properly.
[63 FR 1152, Jan. 8, 1998]
[63 FR 1152, Jan. 8, 1998; 63 FR 20098, April 23, 1998]
How long will a HEPA filter
Envirco offers a variety of High Efficiency Particulate Air (HEPA) and Ultra Low Penetration Air (ULPA)
ducted ceiling modules
and panel filters
to complete your cleanroom design
A HEPA filter can last three to five years or more in a standard cleanroom environment. Life of the HEPA also depends on ambient conditions and maintenance of the prefilters. Since airflow capacity decreases and static pressure increases over time, HEPA filters actually become more efficient as the filter loads. The filter should be changed once it has reached its capacity. For example, if a HEPA unit is set to for 90 ft/min (0.45 m/sec) on the <High> setting, but is only achieving 70 ft/min (0.35 m/sec) on <High>, then the HEPA filter should be changed.
often do I need to change the prefilter?
In dirtier environments, the prefilter may need to be changed as often as every one to three months. Frequency will depend on ambient conditions.
Respirator cartridges don't last forever!
change schedule is the part of the written respirator program which
says how often cartridges should be replaced and what information was
relied upon to make this judgment. A cartridge's useful service
life is how long it provides adequate protection from harmful chemicals
in the air. The service life of a cartridge depends upon many factors,
including environmental conditions, breathing rate, cartridge filtering
capacity, and the amount of contaminants in the
air. It is suggested that employers apply a safety factor to
the service life estimate to assure that the change schedule is a
If you know what the chemical is and how much of it you are exposed to, then you are ready to estimate out how long your respirator cartridges will work and apply the safety factor.
|Keep In Mind|
|Conducting Experimental Tests
to determine a cartridge's service life
Probably the best way to determine service life for multiple chemicals or specific conditions. Some published data from breakthrough studies for organic vapor cartridges have been tabulated here.
|1. Obtain the following information:
||Carl is part owner of a carpet manufacturing plant where a third of the employees wear full mask respirators to protect them from trichloroethylene. They are changing the respirator cartridges about every two hours based on an estimate using a math model. Carl believes the cartridges probably have a longer service life and would like to have more accurate, experimental tests performed. Because some of the workers perform extremely physical tasks on a regular basis, Carl has identified the breathing rate as very high.|
|2. Determine who will conduct the experimental tests.
||Carl recently contacted a local certified analytical laboratory. He works out a deal with them to have the cartridges tested in their lab.|
|3. Provide the tester with the following:
||Carl visits the laboratory and gives some cartridges and the existing data to the lab director, including the maximum relative humidity of the work environment.|
|4. Obtain the results and create a written change schedule for the cartridges.||Carl visited the lab some days later and was pleased to find out that the cartridge protection actually lasted close to 4 hours before the chemical broke through the cartridge! Carl multiplied a safety factor of 3/4 to the estimate and set his change schedule at 3 hours. This meant that he could purchase a third fewer cartridges. Carl took the lab reports and change schedule and incorporated them into his written respirator program.|
|If the chemical's boiling
point is > 70 °C and the concentration is less than 200 ppm you
can expect a service life of 8 hours at a normal work rate.
|Service life is inversely
proportional to work rate.
|Reducing concentration by
a factor of 10 will increase service life by a factor of 5.
|Humidity above 85% will reduce service life by 50%|
Experimental procedures that determine, under actual workplace conditions, whether respirator cartridges are effectively protecting the worker are perhaps the best measure of cartridge performance. Two procedures which have been included in the American Industrial Hygiene Association seminar "Respirator Cartridges: How to Set a Replacement Schedule" are outlined below. You should use these procedures on a systematic and frequent-enough basis to verify your change schedule estimates. Your change schedule estimates must be re-evaluated whenever operations change, or when work place conditions are different than those used by equipment manufacturer's to determine change schedules.
The OEL is normally the health based workplace permissible exposure limit (PEL) or short term exposure limit (STEL) required by OSHA standards. In cases where there is no OSHA workplace exposure limit, use other exposure limits published by the American Conference of Governmental Industrial Hygienists (ACGIH), the American Industrial Hygiene Association, or the National Institute of Occupational Safety and Health.
Procedure 2: Place a quantitative fit-testing (QNFT) sampling adapter between the cartridge and the face piece (Fig. 2). These adapters are often available through your respirator supplier.
You can connect the direct reading instrument using a short piece of tubing made of teflon or other inert material to the outer hose connection on the adapter which, in turn, connects to a small inert sample tube on the inside of the adaptor. Keep the length of tubing as short as possible to minimize the "dead space" in the tubing. The sample tube passes through the respirator’s inhalation valve and is firmly positioned via a small suction cup and clip so that a sample can be drawn directly from the breathing zone of the respirator (i.e., between the cartridge and the respirator).
The recommendations have not been subjected to formal Agency peer review, although peer involvement and informal peer review have occurred. Any policy issues discussed within this document have not been reviewed by the Agency and do not reflect official Agency policy. These recommendations are subject to change as new information is developed that warrants modification of the testing protocol.
Under Section 5 of the Toxic Substances Control Act (TSCA), the Environmental Protection Agency (EPA) may require the use of respiratory protection to protect against inhalation exposure to substances submitted as Premanufacture Notifications (PMNs), or new chemical substances. For new chemicals which are volatile, EPA requires the use of NIOSH/MSHA approved supplied-air respirators unless the company can demonstrate that a NIOSH approved air-purifying respirator with organic vapor cartridges is appropriate. This determination is based on EPA approval of the results of cartridge service life testing performed in a laboratory. EPA requires companies to select, maintain and use respiratory protection in accordance with NIOSH and OSHA requirements at 30 CFR 11, and 29 CFR 1910.134, respectively.
There is often little or no information available with which to determine whether adequate warning properties exist for new chemical substances. In addition, there is often considerable uncertainty regarding the potential human health effects for new chemicals. Finally, odor threshold data as reported in the literature has been found to vary considerably due to the type of data source, the characteristics of human olfactory response, and differences in experimental methodology(1), Due to these uncertainties, the Agency has determined that odor threshold or other testing to identify warning properties is not warranted. Instead, service life testing of organic vapor cartridges or canisters for the new chemical substance during the anticipated conditions of exposure and a cartridge change out schedule determined on the basis of the testing, is required.
There are many factors that affect cartridge service life, such as temperature, relative humidity, challenge concentration, and other environmental and use factors(2-6). In addition, other contaminants can greatly influence the performance of the cartridge and should be considered when conducting cartridge service life testing. While there is no standard test methodology for determination of organic vapor cartridge service life, a testing protocol was published in a peer reviewed technical journal(7). The performance of an organic vapor respirator cartridge in removing a selected airborne substance via adsorption or chemical reaction can be determined by measuring the breakthrough time of the substance through the cartridge under various test conditions.
Summary of Method.
These Interim Recommendations for performing organic vapor cartridge service life testing are based on recommendations presented in the published article(7), a draft Decision Logic prepared by NIOSH for the EPA(8), and professional judgment. The current recommendations require at least 8 tests during the PHASE I testing. Depending on the use conditions, additional testing may be required in PHASE II to investigate desorption characteristics at elevated temperatures. Specific requirements for PHASE II testing will be established by EPA on a case-by-case basis, although it is anticipated that testing at elevated temperatures will be necessary for many new chemicals substances.
The testing protocol represent reasonable worst case environmental testing conditions and minimum testing requirements; companies are encouraged (but not required) to perform additional testing to more fully characterize the sorbent/contaminant breakthrough characteristics(7). The safety factor of 60% of the cartridge service life for field application has been retained from Revision 1 to account for variability between laboratory measurements and actual field performance. These recommendations apply only to cartridges and canisters approved by NIOSH/MSHA under 30 CFR 11. As NIOSH modifies the certification standards and adopts 42 CFR 84, these requirements will be reevaluated.
In April, 1994, the Industrial Hygiene Task Group of the Chemical Manufacturers Association (CMA) submitted suggested changes to the Revision 1 Interim Recommendations (dated May 1, 1991)(9). The CMA Industrial Hygiene Task Group in February, 1995 again stated their preference for a protocol consisting of a single set of tests at the maximum use concentration for the cartridge under the reasonably anticipated worst case environmental conditions(10). Testing would be done in triplicate, with a demonstrated excess service life of 50%. Furthermore, the CMA stated that the EPA protocol was excessive and was more reflective of a research protocol. EPA carefully reviewed the recommendations, consulted with experts at Los Alamos and NIOSH, reviewed the available literature, and responded to the CMA comments in a joint letter with NIOSH dated May, 1994(11). EPA revised the Interim Recommendations accordingly. While EPA strongly supports reducing testing costs while still maintaining acceptable worker protection, EPA believes that it is necessary to test at more than one concentration, humidity, and temperature to determine the reasonably anticipated worst case conditions. For example, low relative humidity, rather than high, may be worst case conditions for some substances, and the same is true with temperature. The CMA suggestions are a viable option only if it can be demonstrated that the selected environmental conditions are indeed worst case; EPA knows of no reliable means of demonstrating this without testing. The EPA Interim Recommendations are subject to modification on a case by case basis, and companies are encouraged to carefully evaluate the protocol as it applies to their case and consult with EPA as needed.
Section 1. Initial Screening for Cartridge or Canister Service Life.
Several models have been developed for predicting organic vapor cartridge service life(12-23). However, their applicability for predicting cartridge service life for untested compounds is limited, especially for new chemical substances where data useful in predicting service life (e.g. vapor pressure, capacity and adsorption rate, etc.) is generally limited or unavailable. Recently, a model was published based on the modified Wheeler equation and incorporated advancements in predicting organic vapor cartridge service life for untested compounds, provided minimal information on the challenge compound and on the adsorption carbon were available(24). However, the model currently only considers dry conditions (relative humidity < 50%).
Predictive models can be useful to initially screen whether a cartridge might be appropriate for a new chemical substance. If the model predicts service life at less than 20 minutes for the new chemical substance, then an organic vapor cartridge may not be appropriate for the substance, and the company may want to reconsider the use of a supplied-air respirator instead of performing cartridge service life testing on cartridges or canisters.
Section 2. High Heats of Reactions with the Sorbent.
The company shall document that the new chemical substance will not result in high heats of reaction (> 20°C above ambient temperature) with the sorbent material of the cartridge or canister. For substances which generate high heats of reaction, only non-oxidizing sorbent materials shall be used.
Section 3. Preparation of Cartridges or Canisters for Testing.
Cartridges and canisters shall be tested as received (dry bed conditions). Cartridges used in pairs on an air-purifying respirator should be tested in parallel in pairs, or the airflow rates should be halved for testing them singly.
Section 4. Testing Parameters for Cartridge or Canister Service Life Testing.
The minimum required replicates and testing parameters for performing cartridge and/or canister service life testing are:
PHASE II testing requirements will be established on a case-by-case basis. At a minimum, if the cartridge and/or canister will be used as protection against inhalation exposure at elevated temperatures (> 35°C) , the following additional testing is required:
a Where x = New Chemical Exposure Limit (NCEL), or the predicted airborne concentration if no NCEL exists.
b More than two replicates shall be tested if the variability between results for each set of replicates exceeds 10%.
c If the results of PHASE I testing demonstrate that the service life under low (e.g. 20%) relative humidity conditions is less than the service life at 80% relative humidity, then PHASE II testing shall be conducted under low (20 ± 5%) relative humidity conditions instead of the higher relative humidity conditions specified.
Section 5. Cartridge Change Out Schedule.
The company shall establish a cartridge/canister change out schedule based on the results of the service life testing for reasonable worst case testing conditions, any administrative controls that will be used, and incorporating the safety factor of 60% of the measured service life to account for variability in environmental conditions. Cartridges or canisters shall be changed prior to the end of service life, or at the end of the shift, whichever comes first. The cartridge change out schedule and other administrative actions shall be incorporated into the Respiratory Protection Program, as required by 29 CFR 1910.134.
If extended cartridge change out schedules (longer than 1 work shift) are desired, the company should consult with EPA as additional testing will be required to demonstrate that desorption and migration of contaminant vapor between shifts and during repeated storage and reuse does not occur. There has been little or no research in this area, and standard testing protocols are currently unavailable.
Section 6. Reporting of Data.
The following data and information shall be submitted to EPA for review and approval of cartridge and/or canister service life testing data:
i) the actual breakthrough curve and the tabulated concentration versus time for each set of testing parameters;Section 7. EPA Approval.
Upon receipt of EPA approval of the cartridge service life data and the cartridge change out schedule, the company may use NIOSH/MSHA approved air-purifying respirators equipped with an organic vapor cartridge or canister for protection against inhalation exposure to the new chemical substance instead of NIOSH/MSHA approved supplied-air respirators. The organic vapor cartridge used shall provide equivalent or greater sorption capacity to the cartridge or canister tested.
Section 8. Other Use Conditions.
The cartridge and/or canister is approved only for use in use conditions similar to those reflected by the testing parameters (e.g. single contaminant (the new chemical substance) at a range of airborne concentrations, low to high relative humidity, and selected ambient temperature(s)).
Organic vapor-acid gas cartridges and/or canisters may be used for protection against the new chemical substance provided the sorption capacity of the organic vapor-acid gas cartridge or canister is equivalent or greater than that of the tested cartridge or canister.
However, if there is potential for inhalation exposure to multiple contaminants (e.g. the new chemical substance and an acid gas), additional service life testing would be necessary to demonstrate that the cartridge or canister selected is appropriate. Only limited evaluation of the breakthrough characteristics of multiple contaminant systems has been conducted to date(25-26).
1. American Industrial Hygiene Association: Odor Thresholds for Chemicals with Established Occupational Health Standards. American Industrial Hygiene Association: Fairfax, VA. (1989).
2. Nelsen, G.O., and C.A. Harder: Respirator Cartridge Efficiency Studies: V. Effects of Solvent Vapor. Am. Ind. Hyg. Assoc. J. 35:391-410 (1974).
3. Moyer, E.S.: Review of Influential Factors Affecting the Performance of Organic Vapor Air-Purifying Respirator Cartridges. Am. Ind. Hyg. Assoc. J. 44:46-51 (1983).
4. Nelson, G.O. and A.N. Correia: Respirator Cartridge Efficiency Studies: VII. Summary and Conclusions. Am. Ind. Hyg. Assoc. J. 37:514-525 (1976).
5. Hall, T., P. Breysse, M. Corn, and L.A Jonas: Effect of Adsorbed Water Vapor on the Adsorption Rate Constant and the Kinetic Adsorption Capacity of the Wheeler Kinetic Model. Am. Ind. Hyg. Assoc. J. 49:461-464 (1988).
6. Nelson, G.O., A.N. Correia, and C.A. Harder: Respirator Cartridge Efficiency Studies: VII. Effect of Relative Humidity and Temperature. Am. Ind. Hyg. Assoc. J. 37:280-288 (1976).
7. Wood, G.O. and Ackley, M.W.: A Testing Protocol for Organic Vapor Respirator Canisters and Cartridges. Am. Ind. Hyg. Assoc. J. 50:651-654 (1989).
8. Bollinger, N. and Coffey, C.: Decision Logic for Organic Vapor Cartridge Respirators for Premanufacture Notification (PMN) Substances. DRAFT (May 25, 1988, unpublished).
9. Chemical Manufacturers Association. Letter to Mr. Gerry Wood, Los Alamos National Laboratory from Thomas J. Nelson, 3M, and Karen M. Cragg, CMA. (April 11, 1994).
10. Chemical Manufacturers Association. DRAFT Comments submitted to Mr. Roy Seidenstein, EPA from Mr. R. Holmes, on the proposed Generic Section 5(e) Order with New Chemical Exposure Limits, as a supplement to comments previously submitted. (February 6, 1995).
11. National Institute for Occupational Safety and Health. Letter to Ms. Karen M. Cragg and Mr. Thomas J. Nelson, Chemical Manufacturers Association from Ernest S. Moyer, Ph.D. and Cathy Fehrenbacher, EPA.
12. Smoot, D.M., Smith, D.L., and Scheh, T.A.: Development of Improved Respirator Cartridge and Canister Test Methods. U.S. Dept. of Health and Human Services, Public Health Service. Center for Disease Control. National Institute for Occupational Safety and Health. Publication No. 77-209.
13. Ackley M.W.: Residence Time Model for Respirator Sorbent Beds. Am. Ind. Hyg. Assoc. J. 46:679-689 (1985).
14. Yoon, Y.H. and J.H. Nelson: Application of Gas Adsorption Kinetics: I. A Theoretical Model for Respirator Cartridge Service Life. Am. Ind. Hyg. Assoc. J. 45:509-516 (1984).
15. Yoon, Y.H. and J.H. Nelson: Application of Gas Adsorption Kinetics: II. A Theoretical Model for Respirator Cartridge Service Life and Its Practical Applications. Am. Ind. Hyg. Assoc. J. 45:517-524 (1984).
16. Wood, G.O.: A Model for Adsorption Capacities of Charcoal Beds: II. Challenge Concentration Effects. Am. Ind. Hyg. Assoc. J. 48:703-709 (1987).
17. Yoon, Y.H. and J.H. Nelson: A Theoretical Study of the Effect of Humidity on Respirator Cartridge Service Life. Am. Ind. Hyg. Assoc. J. 49:325-332 (1988).
18. Wood, G.O.: A Model for Adsorption Capacities of Charcoal Beds. I. Relative Humidity Effects. Am. Ind. Hyg. Assoc. J. 48:622-625 (1987).
19. Moyer, E.S.: Organic Vapor (OV) Respirator Cartridge Testing - Potential Jonas Model Applicability. Am. Ind. Hyg. Assoc. J. 48:791-797 (1987).
20. G.O. Wood and E.S. Moyer: A Review of the Wheeler Equation and Comparison of Its Applications to Organic Vapor Respirator Cartridge Breakthrough Data. Am. Ind. Hyg. Assoc. J. 50:400-407 (1989).
21. Wood, G.O. and E.S. Moyer: A Review and Comparison of Adsorption Isotherm Equations Used to Correlate and Predict Organic Vapor Cartridge Capacities. Am. Ind. Hyg. Assoc. J. 52:235-242 (1991).
22. Wood, G.O.: Activated Carbon Adsorption Capacities for Vapors. Carbon 30:593-599 (1992).
23. Wood, G.O.: Organic Vapor Respirator Cartridge Breakthrough Curve Analysis. J. Int. Soc. Resp. Prot. Winter :5-17 (1992-93).
24. Wood, G.O.: Estimating Service Lives of Organic Vapor Cartridges. Am. Ind. Hyg. Assoc. J. 55:11-15 (1994).
25. Yoon, Y.H., J.H. Nelson, J. Lara, C. Kamel, and D, Fregeau.: A Theoretical Interpretation af the Service Life of Respirator Cartridges for the Binary Acetone/m-Xylene System. Am. Ind. Hyg. Assoc. J. 52:65-74 (1991).
26. Yoon, Y.H., J.H. Nelson, J. Lara, C. Kamel, and D. Fregeau.: A Theoretical Model for Respirator Cartridge Service Life for Binary Systems: Application to Acetone/Styrene. Am. Ind. Hyg. Assoc. J. 53:493-502 (1992).