Respiratory Protection I

PO101
Respiratory Protection I

Monday, June 1, 2015, 10:30 AM - 12:30 PM

SR-101-01 Using Chemical Challenge Breakthrough Data and Simple Models to Establish and Support Respirator Change Schedules

B. Quarles, Assay Technology, Livermore, CA; C. Manning, Assay Technology, Livermore, CA

Objective: A respirator change schedule is the part of the written respirator program which states how often cartridges should be replaced, and what information was relied upon to make this judgment. A cartridge’s useful service life is equivalent to the length of time 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. In rule 29CFR 1910.134, and summarized on its web-site, OSHA suggests that there are three ways to generate a valid respirator cartridge change schedule: (a) Laboratory Testing, (b) Manufacturer’s Recommendations; (c) Math Model such as the OSHA Advisor genius. Lab testing is the first of the three methods recommended by OSHA, as it is would be expected to be the most accurate. However, it is the least popular, because of the perception that it will be more expensive than other methods. The objective of this work was to develop a method for efficient economical prediction of service life from a minimum number of laboratory tests.

Methods: Since the cost of lab testing may approach $1,000 per day, testing for longer than one day may be seen as too costly. Where it is desired to validate a service life longer than one day, we developed a procedure for extrapolation of data from lab tests using higher agent concentrations than the levels anticipated in actual use. This strategy led to shorter breakthrough times allowing several tests to be performed within one day.

Results: Using this approach, the investigators were able to plot log [Challenge Level] versus log [Breakthrough Time] to obtain a line that could be extrapolated to obtain a projected breakthrough time at the expected maximal concentration of agent present in a real-world environment.

Conclusions: Reasonably linear plots allowing accurate extrapolation were obtained for several different challenge agents, so we conclude that this procedure is applicable to typical situations. By collecting multiple data points within one day instead of over more than one day, the economic impact on the end user for using lab testing for prediction of service life is reduced. The method does have the limitation that it may not be applicable in situations where the mechanism of agent removal by the respirator cartridge is other than physical adsorption or chemisorption.


SR-101-02 Determination of the Service Life of Air-Purifying Respirators against 2,3-Pentanedione

J. Parker, NIOSH, Pittsburgh, PA

Objective: 2,3-Pentanedione is a diketone used as a synthetic flavoring agent and aroma carrier. It has a buttery taste and smell and is structurally very similar to diacetyl (2,3-butanedione). 2,3-Pentanedione and diacetyl have been implicated in causing pulmonary disease in workers handling these compounds. The objectives of this study are to evaluate the performance of air-purifying organic vapor / P100 respirators against 2,3-pentanedione and to compare experimental data with service life data from a similar study performed by NIOSH in 2009 against diacetyl.

Methods: Service life testing was performed at NIOSH-NPPTL laboratories in Pittsburgh, PA, using a methodology similar to the techniques employed for certification testing of gas /vapor respirators. Photoacoustic infrared detectors were used to measure upstream and downstream concentrations. Testing was performed at concentrations of 500 to 890 parts per million by volume (ppmv), and at 50% relative humidity and approximately 25 degrees C.

Results: Results are presented and compared for three different makes and models of NIOSH approved air -purifying respirators tested against 2,3-pentanedione. It was found that organic vapor / P100 air-purifying respirators have a service life of 150-240 minutes versus 2,3-pentanedione at concentrations of 500-890 ppmv. Data is also presented concerning impurities found in the reagent and how this affected the service life results.

Conclusions: Conclusions of this study are that NIOSH approved organic vapor / P100 air-purifying respirators are capable of providing respiratory protection against 2,3-pentanedione. Proposed maximum use concentrations for air-purifying respirators used for protection against diacetyl and 2,3-pentanedione will be discussed. These are based on the NIOSH Recommended Exposure Limits for 2,3-pentandione and diacetyl that were proposed by NIOSH in 2011 in the external review draft of the “NIOSH Criteria for a Recommended Standard for Occupational Exposure to Diacetyl and 2,3-Petanedione.”


SR-101-03 Paper-Based Optical Sensor as an End-of-Service-Life Indicator for Hydrogen Cyanide

L. Greenawald, CDC/NIOSH, Morgantown, WV

Objective: In an occupational or military environment, an air-purifying respirator is required when breathing-air is polluted by harmful contaminants. However, it is difficult for the user to identify when the canister becomes saturated and ceases to provide adequate protection to the user. The objective of this research is to develop an inexpensive active end-of-service-life indicator (ESLI) to optically detect hydrogen cyanide gas (HCN) before it reaches the user’s breathing zone. ESLIs more accurately allow the respirator user to know when a canister must be replaced.

Methods: Cobinamide (Cbi), a Vitamin B12 derivative, is known to bind two cyanide ions (CN-) with high affinity. When binding of two CN- occurs, a violet color rapidly persists with a corresponding peak observed in the visible region on an absorbance spectrum. An optimized concentration of Cbi solution was adsorbed onto paper. The Cbi-doped paper was placed into a holder that allows for diffusion of HCN. A bifurcated fiber optic was connected to the sensor holder, along with corresponding light source and spectrometer. A gas flow system was designed to deliver known concentrations of HCN to the sensor. When HCN diffuses into the pores of the Cbi-doped paper, optical-based time measurements were made by monitoring the absorbance at a specific wavelength to detect low levels of HCN. The sensor holder was then externally connected to a commercial CBRN canister at approximately 90% saturation volume so detection could be made before breakthrough occurs.

Results: A prominent absorbance peak exists when the Cbi-paper sensor is in the presence of various concentrations of HCN gas. Calibration plots were performed. 5 ppm HCN can be detected in 2 minutes. Percent relative humidity levels ranged from 25-80% to determine the effects of the sensor’s ability to detect low levels of HCN in various simulated climates. When the sensor and associated electronics were externally connected to the canister, HCN was flowed through the canister at 32 and 64 lpm. The Cbi sensor detects HCN at an appropriate time before breakthrough occurs.

Conclusions: The respirator user will be notified when the concentration of HCN reaches its NIOSH recommended exposure of 4.7 ppm. Ultimately, a low-power LED light source, compact spectrometer and paper sensor coupled to an optical fiber will be integrated to a CBRN canister to detect breakthrough of HCN gas and ESL of the canister.


SR-101-04 Effects of Air Temperature on Efficiency and Service Life of Air Purifying Chemical Respirator Cartridges Tested Against Sulfur Dioxide and Ammonia

M. Parham, Scott Safety, Monroe, NC

Objective: Determining an accurate change out schedule for respiratory cartridges is a critical part of any well written respirator program utilizing filtering respiratory protective devices. The service life of any cartridge is dependent upon many factors such as environmental conditions, breathing rate, and contaminant concentration. Where possible it is widely recommended to make use of math models, manufacturer’s recommendations, and/or experimental tests. While experimental tests are considered the more accurate approach, it is typical that these tests are conducted at ambient temperature and at higher concentrations than typically encountered in the field. Math models and those models used by manufacturers typically make corrections for temperature however the basis of these corrections are not always clearly communicated or appropriate for chemisorbed contaminants such as sulfur dioxide and ammonia.

Methods: Air purifying chemical respirator cartridges with differing types of impregnated activated carbon were laboratory tested against sulfur dioxide and ammonia at ambient and elevated temperatures (up to 50°C) as received (ambient temperature) and pre-equilibrated to elevated temperatures. Filtering efficiency (initial penetration) and service life time were captured for typical certification test concentration and concentrations more in line with typical air purifying respirator use.

Results: For sulfur dioxide, temperature effect was found to be not significant at the higher concentration but some evidence of decreased capacity was observed at lower concentration. Ammonia service life was directly affected by temperature with higher reductions observed for filters equilibrated to the higher elevated temperature. In both cases departures from predicted math model behavior was observed.

Conclusions: The findings of this study support the importance of testing cartridges, if possible, under conditions similar to expected use. They also identify areas for future research in service life modeling and suggest that higher concentrations are not always design limiting when considering use scenarios.


CS-101-05 Respirator Cleaning Methods: An Overview of Primary Respirator Cleaning Requirements and Methods Currently Used

D. Stein, 3M, St. Paul, MN

Situation/Problem: A significant but often deemphasized aspect of an effective respiratory protection program is cleaning. The decontaminating, cleaning and sanitizing of respiratory protection devices is important to help prevent secondary exposure to contaminants. Contaminant inhalation as well as skin contact can result from ineffective cleaning procedures. Additionally, basic respirator function can be adversely affected by a lack of thorough cleaning and post cleaning inspection procedures. Cleaning methods based on manufacturer’s instructions are typically implemented with hand washing and drying, while some employers may determine to run systematic cleaning departments with or without cleaning machines and/or cleaning services. This is based on the variety of options available in the market for respirator cleaning and the needs of the employer.

Resolution: This presentation will provide an overview of the importance of respirator cleaning, regulatory requirements related to respirator cleaning, and the breadth and depth of respirator cleaning methods present in today’s industry.

Results: When done, attendees will understand: - Importance of cleaning - Regulatory Requirements - Breadth and depth of types of respirator cleaning

Lessons Learned: The importance of proper cleaning techniques for respirators, regulatory requirements for the issue, and awareness of industry practices in respiratory protection programs will be delineated.