Respiratory Protection Newsletter from Dr. McKay

Summer-Fall, 2003, edition

SARS

Evidence Suggests Fit Testing Could Have Been Helpful: The majority of SARS infections occurred in locations with insufficient infection control precautions or where they were not followed. The Canadian experience is different and suggests that fit testing could have potentially made a difference.

The May 16, 2003 Morbidity and Mortality Weekly Report (MMWR) summarizes a cluster of SARS infections among health care workers in Toronto despite apparent compliance with Canadian infection control procedures. Some differences in the Canadian procedures that may have played a role are that fit testing and NIOSH approved respirators were not required.

The report follows the transmission of SARS from three infected patients to their treating physician. SARS was then transmitted to other health care workers who subsequently treated the infected physician. Possible causes of transmission to the health care workers included the lack of formal respirator training and workers not being fit tested. One nurse responsible for caring for the patient had a small beard and reported that his mask did not fit well. Although he wore a PCM2000 (TM) duckbill mask and a surgical mask with face shield, he reportedly stated he could feel air coming through the sides of the facepiece. In the US, tight fitting filtering facepieces such as NIOSH approved N95 respirators must not be worn in the presence of facial hair at the sealing surface and they must be fit tested. As a reminder, fit testing requires the use of additional testing equipment and should not be confused with actions conducted by the user to check the adequacy of fit, position, and/or strap adjustment (ie, user seal checks). User seal checks detect primarily gross leakage and are difficult to objectively evaluate on filtering facepieces. They are not, however, as accurate as fit testing.

Additionally, Health Canada recommendations, although similar to those of CDC, differ from the CDC guidelines which specify the use of respirators approved by NIOSH rated at an N95 level of protection or greater. Health Canada recommends use of "N95 equivalent" respirators. The respirators used in this hospital, although compliant with Canadian public health recommendations, were not NIOSH approved.

While the lack of fit testing cannot be proven as the reason for transmission, it certainly may have played an important role. Health Care Workers (HCW) are frequently exposed to aerosol generating procedures. During these procedures respirators and other forms of personal protective equipment must be worn. Proper use of this equipment is essential. While some workplace protection factor studies support an APF of 10 for filtering facepiece respirators, just look around and watch the number of workers who incorrectly wear and use these respirators. If they don't fit or are not worn correctly, respiratory protection will be diminished.

To view the complete MMWR article, visit the CDC website

http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5219a1.htm.

Fatal Injuries Involving Respirators:

A recent article in Applied Occupational and Environmental Hygiene 18(4):289-292, 2003 entitled Fatal Injuries in the US Involving Respirators summarizes 41 incidents resulting in 45 deaths while wearing a respirator. The study period investigated OSHA case files from 1984 through 1995. The authors (Suruda Anthony, W. Milliken, D. Stephenson, & R. Sesek) provide a comprehensive and interesting summary of asphyxiation and chemical poisonings. For those of us who conduct respirator training, the incidents provide useful insights towards worker tendencies. Deaths associated with failure to use a respirator were excluded, as were fatalities associated with structural fire fighting.

There were 3 deaths among workers with beards who wore negative pressure respirators in an IDLH environment. Airline delivery of air was responsible for 51% of deaths. Most of these were due to inappropriate couplings that permitted connection to non-grade "D" breathing air such as nitrogen. Eight deaths involved compressor malfunctions and/or design systems. While details of the incidents are only briefly described, the article is still very interesting. Another interesting aspect is that medical screening would not have apparently prevented any of these deaths. The authors also reveal that the number of fatalities for the 12 year period is probably greater than reported since OSHA does not investigate all workplace fatalities. If you have an interest in such things, you may wish to obtain a copy of the article. The article is copyright protected, so I'm unable to provide copies.

Thinking of Buying an Escape Hood?

During lecture presentations around the country, I'm frequently asked about escape hoods and other respirators to protect against potential terrorist threats, including biological and chemical agents. Those of us with experience in the field have nightmares wondering if these devices will be properly used. One only needs to look at workplaces with poor respirator programs or the news media to see examples of incorrectly worn and used respirators. During the recent SARS epidemic I lost count of the number of respirators worn upside down, over beards, etc. In some cases, people ask if a gas mask or escape hood will protect the wearer from hotel fires. The user must read the manufacturer's information (product literature and user instructions) to determine if protection is provided from a smoke filled building. In some cases, the smoke may quickly clog the filters or adsorbent media making it difficult to breathe through. In other cases the device may not remove carbon monoxide and/or other toxic gases. In some cases, certain gas masks or hooded devices may soften, become deformed, or even melt when exposed to the heat of a structural fire. Recently, NIOSH has once again come to the rescue with the release of a "Respirator Fact Sheet" for persons considering to buy escape hoods, gas masks, or other respirators for preparedness at home or work. To obtain a copy of this useful 4 page fact sheet, contact NIOSH at 1-800-356-4674 or visit their web page at: www.cdc.gov/NIOSH and request a copy of publication number 2003-144.

OSHA Proposes New Assigned Protection Factors:

On June 6 OSHA published proposed changes to amend the Respiratory Protection Standard (1910.134) to incorporate new Assigned Protection Factors (APFs) for respiratory protection programs. In the notice of proposed rule making, OSHA proposed amending the existing standard to assist employers in the proper selection of respirators. APF's are numbers that reflect the expected level of protection that a properly fitted, worn, used, and trained worker would likely achieve. The proposal contains OSHA's preliminary decisions on an APF Table, definitions, Maximum Use Concentrations (MUCs) for respirators, and amendments to replace existing APF requirements in OSHA's substance specific standards. For information about the proposed changes, go to the OSHA web page at: www.OSHA.gov 

The most controversial change in the APFs will likely be for filtering facepieces. OSHA has proposed an APF of 10. Interestingly, the recent ANSI Z88.2 draft proposes an APF of 5 for filtering facepieces. As we reflect on the recent SARS experience, many of us are reminded of how filtering facepieces are actually worn and used in real life. The potential level of protection and the actual level provided may differ. Certainly proper use and fitting is essential. Hopefully, users will learn to recognize that fit testing is necessary for these respirators and that user seal check procedures are not a replacement for fit testing.

OSHA plans to hold an informal public hearing on the APF proposal in Washington, D.C. in late summer or early fall. Interested parties who intend to present public testimony at the hearing must notify OSHA of their intention to do so no later than September 4. The meeting date and location will be announced at a later date.

Written comments must be submitted by September 4, 2003. Comments can be faxed to OSHA's Docket Office at 202-693-1648 or sent electronically to http://ecomments.osha.gov . Comments should not exceed 10 pages. Written comments can also be sent via US Mail. Additional information on submitting comments can be obtained by calling the Docket Office at 202-693-2350.

OSHA Proposes New Fit Testing Procedure:

On June 6 OSHA also published a proposal to include a new fit testing protocol for users of the Controlled Negative Pressure (CNP) method. Please note that these changes do not affect other methods commonly used to fit test respirators. For example, users of the TSI PortaCount are not affected by the proposed revisions. For information about the proposed changes, go to the OSHA web page at: www.OSHA.gov

NIOSH Revokes Respirator Approvals:

Recently NIOSH revoked certification for two N-95 filtering facepiece respirators manufactured by Wen Mask Industrial Company. The affected models are KR-795 and KR-808. The previous NIOSH approval numbers for these respirators were: TC-84A-2531 and TC-84A-2532, respectively. The certifications were revoked because the respirators failed to meet the performance requirements of Title 42, Code of Federal Regulations, Part 84.

So what does this mean? Besides no longer being listed as NIOSH approved, revocation means respirators bearing these approval numbers may no longer be manufactured, sold or distributed for use in workplaces where OSHA requires respiratory protection. If you currently use these facepieces, I suggest you stop using them in areas that require respiratory protection.

Because these respirators are sold under many different names, my suggestion is to look at your filtering facepieces and determine if any of your facepieces have the approval numbers listed above. At least 6 different companies market these respirators under a variety of names. In each case, the model number's KR-795 and KR-808 are used. So if you see these model numbers or approval numbers, take action. Additional details are available from the NIOSH Respirator Branch at 412-386-4000.

NIOSH Recommends Discontinued Use of 30 CFR Part 11 Dust/Mist filters:

This may be a little late, but some reader of this newsletter may not be aware of a September 4, 2002 Respirators Users Notice from NIOSH. NIOSH investigated a report involving the presence of a fine yellow-white dust on "packaged", unused dust/mist filters that were approximately 4 years old. Dust/Mist filters have not been produced for sale in the US since July 10, 1998, but some of you may have these filters sitting around in storage.

The source of the yellow-white dust apparently represents a zinc/calcium salt resin that was applied to the individual filter fibers. With storage time, the filter fibers crumble and produce small particles on the surface. Since NIOSH could not obtain additional samples of these filters to perform filter testing, it is unknown if the filters would continue to pass the performance requirements of 30 CFR Part 11. No known health risks associated with the zinc/calcium particles have been reported.

NIOSH recommends that any respirator user who is using filters produced and approved under the "old" testing guidelines (30 CFR Part 11), replace them with filters approved under the newer test guidelines (42 CFR Part 84). For example, the newer filters are designated as N, R, or P rather than "dust/mist". NIOSH further recommends that users who have questions about the performance and/or shelf life of filter respirators approved under 30 CFR Part 11 (ie, dust/mist filters) should contact their manufacturer directly.

As a general rule of thumb, I have always recommended dating incoming packages of filters and cartridges. Now you know one reason why!

ANSI Respirator Standards Update:

Z88.2 Practices for Respiratory Protection. The public review period ended June 16. The subcommittee voted to approve its draft standard and is now addressing comments.

Z88.6 Respirator Use - Physical Qualifications for Personnel. The full committee approved the draft standard. The subcommittee is now resolving a few negative votes.

Z88.8 Test Methodologies for Air Purifying Respirators. The subcommittee is currently processing comments.

Respiratory Protection - Again among OSHA's Top Ten Most Violated List:

The Respirator Standard once again made OSHA's top ten list of violated standards as the 4th most violated standard during fiscal year 2002. The Respirator standard directs employers to establish a written respirator program with work site-specific procedures. This means there must be written procedures regarding the selection of respirators used at the workplace, change out schedules, etc. Apparently, many employers didn't have these procedures in writing.

NIOSH User Notice for MSA Life-Saver 60 Self Contained Self Rescuer (SCSR):

On November 14, 2002, NIOSH posted a Respirator User Notice to inform users of the MSA Life Saver 60 Self Contained Self Rescuer (SCSR) that the potential for the quick start candle to become excessively hot "may" exist on units manufactured from October 2000 to July 2002. In extreme cases, the excessive heat may cause nearby components to ignite. The purpose of the quick start candle is to provide an initial supply of oxygen until the unit kicks in. To identify these units, look for the NIOSH approval number TC-13F-385. Serial numbers for the units in question range from 14573 through 15661 and were shipped to customers between September 2000 and July 2002. The serial numbers are stamped on a metal band.

It is my understanding that none of the MSA Life Saver 60 Self Contained Self Rescuer (SCSR) units have actually over-heated. Rather, a similar component has been used by navies around the world. MSA has investigated the problem and identified that a higher than normal amount of iron powder may cause the candle to become too hot. Changes have been made to the product to prevent this problem from happening in the future. Additional information can be obtained from NIOSH at 412-386-6731 or MSA directly at 1-888-421-8324.

Congratulations to Lisa Delaney:

Lisa published the following article in the journal of Applied Occupational and Environmental Hygiene, Volume 18(4):237-243, 2003:

"Determination of Known Exhalation Valve Damage Using a Negative Pressure User Seal Check Method on Full Facepiece Respirators". This study found that negative pressure user seal checks rarely identified damaged exhalation valves. However, the study supported the need for respirator inspection prior to donning with periodic fit testing in addition to the performance of user seal checks as necessary components of an adequate respiratory protection program. Authors were: Lisa Delaney, Roy McKay, and Andrew Freeman. These studies were conducted at Dr. McKay's laboratory at the University of Cincinnati.

OSHA Standards Update on Tuberculosis:

Due to the decline in reported TB cases since 1993 and existing guidelines, OSHA has decided not to proceed with finalizing a standard on TB. Therefore, the proposed TB standard has been withdrawn. The question now is whether or not OSHA will require employers to follow the revised respirator standard and withdraw 1910.139 which contains outdated information. Stay tuned for more information about this. In the interim, remember that OSHA does require annual fit testing for filtering facepiece respirators worn for other potential exposures in health care settings such as agents that cause SARS, other infectious organisms, drugs delivered by aerosol etc.

NIOSH Homeland Security Update:

In January 2003, NIOSH approved the Scott Model Air-Pak 4.5 and the Interspiro models Spirotek S3 9030, 6630, and 4530 respirators for occupational use by emergency responders against chemical, biological, radiological, and nuclear (CBRN) agents. These devices are open circuit SCBA's. NIOSH approval identifies that the devices passed the new CBRN performance tests. NIOSH is continuing to test and evaluate other SCBA's submitted by manufacturers for certification. For a more up to date list of certified respirators, go to the NIOSH web page at www.cdc.gov/NIOSH.