Breathe In, Breathe Out
By Jason Contant
The list of deadly substances a worker may encounter while responding to a hazardous event is varied and frightening: materials that are radioactive, flammable, explosive, corrosive, biohazardous or t...
The list of deadly substances a worker may encounter while responding to a hazardous event is varied and frightening: materials that are radioactive, flammable, explosive, corrosive, biohazardous or toxic, just to name a few.
With the potential for harm, the last thing any responder wants to worry about is taking time out to check the effectiveness of personal protective equipment (PPE) or to wonder how it will perform in harsh conditions. As a critical piece of PPE, respirators would certainly fall into this category.
Signs are encouraging, however, that some such worries may soon become a thing of the past. Sylvain Lefebvre, product manager for respiratory products at North by Honeywell in Anjou, Quebec, expects the market to supply in future more respirators with electronic devices to alert users when either the gear’s batteries or its flow of air are getting too low.
Consider a powered air-purifying respirator (PAPR), which typically works by using a filter to clean ambient air before it is delivered to the user by means of a battery-operated blower, says Lefebvre. If the battery goes dead while in a dangerous environment, “you’re in big trouble because as soon as you breathe in, it’s going to be negative pressure and you’re going to absorb the contaminant inside your respirator,” he says.
A standard requiring low-flow and low-battery indicators on PAPRs has been mandatory in Europe for about two years, but optional in North America, Lefebvre says. The National Institute for Occupational Safety and Health (NIOSH) in Washington, D. C. is currently working on a protocol that he expects to be released soon.
John Hierbaum, product line manager for respiratory protection with Mine Safety Appliances Company (MSA) in Cranberry Township, Pennsylvania, says his organization offers a PAPR equipped with both audible and visual alarms. In addition to sounding warnings for low battery or air, Hierbaum says the unit includes a pressure sensor to regulate the flow of air depending on altitude.
Here at home, the Canadian Standards Association (CSA) is in the process of updating CSA Z94.4, “Selection, Use and Care of Respirators,” last released in 2002. Expected as early as next year, the new version will include descriptions of limitations and capabilities of different respirator types, assigned protection tables (minimum anticipated protection provided by a properly functioning respirator to properly fitted and trained users — see Assigned Protection Factors on page 52) and information on cleaning, inspection, maintenance and storage of respirators.
JUST MY TYPE
The working environment, the type of airborne hazard and its concentration will dictate what respirator option is necessary to keep a user safe. By general type, there are air-purifying respirators (APRs) and supplied-air respirators (SARs).
APRs use filters to remove particulates such as dust, oil or aerosol mists or metal fumes, cartridges to remove gases and vapours, or a combination of the two, says Eric Dzuba, product group manager for air-purifying respirators at Drger Safety Inc. in Pittsburgh. If a work operation involves painting, welding, sweeping, grinding or sanding, this will come into play, signalling the need for a quarter-mask, half-mask or full facepiece, Dzuba says.
Sometimes, it’s a matter of hazard upon hazard — which may require separate or complementary protective gear. Beyond a respirator, Dzuba suggests also considering if a worker needs eye protection during a grinding operation “where stuff is flying around.” Or what about using a full facepiece if a chemical, such as chlorine, is irritating to the eyes?
“Again, it depends on the hazard,” Dzuba emphasizes. “For instance, in spray-painting booths, most times you can wear a half-mask or full-mask cartridge respirator, but if you are spraying with isocyanates, then you need supplied air because it’s a carcinogen.”
SARs, for their part, supply clean air from a compressed air tank or through an air line. This group of gear includes such respiratory protection as a self-contained breathing apparatus (SCBA), which features both open-and closed-circuit options, says Jeff Shipley, SCBA product manager for Sperian Protection, based in Smithfield, Rhode Island.
A closed-circuit SCBA — known as a re-breather — does not have a traditional cylinder of air. Rather, it works by filtering, supplementing and then re-circulating exhaled gas from a user’s breath and then transforming it into breathable air. Usually providing two to four hours of air, this SCBA option is designed to protect a user in oxygen-deficient or toxic environments.
The latter potentially includes mine, tunnel and other underground rescue efforts and hazmat operations “where the user will be working for longer durations and will not have the ability to constantly change cylinders,” says Shipley.
The traditional, open-circuit SCBA, often used by firefighters, is comprised of a cylinder filled with filtered compressed air, he explains. This type of protection contains two regulators: a first-stage regulator to reduce the air pressure so that it can be carried to the mask, and a second-stage regulator to “reduce it even further to a level that allows comfortable breathing.”
ONE FOR ALL
Depending on the work environment, a cartridge may be needed to protect against “one particular family of gases,” says Dzuba. Among these groupings are organic vapours, acid gases or particular chemicals, such as ammonia, formaldehyde or hydrogen sulphide.
If one of those options doesn’t fit the bill, an employer may purchase a multi-gas cartridge. This may be a solid choice if, for example, workers within a particular area of a facility need protection from ammonia, another group must be shielded from chlorine and a third crew requires proper defence from organic vapours. “They don’t want each person to have to think about grabbing the right set of cartridges. They just want one cartridge and it will protect from everything,” Dzuba says.
If employers know full well that protection is needed from a particular family of gases, though, a multi-gas cartridge may not be the best bet, he advises. “You would rather not use a multi-gas cartridge, because if you do, it won’t last as long,” he says.
Dr. Jeffrey Birkner, vice-president of technical services for Moldex-Metric Inc. in Culver City, California, agrees, pointing out that “you start to lose the maximum efficiency that you would have if it was a single gas cartridge.”
On the face of things, with multi-gas cartridges, there’s the convenience of limiting the number of cartridges that must be purchased for a facility, he says. But that approach may end up costing more because of the service life of the cartridge.
ALL IN THE TIMING
For cylinders, they are usually designed to provide 30, 45 or 60 minutes of continuous air, although actual “air time” may not be that long “depending on the exertion and fitness of the wearer,” Shipley says. “A 30-minute cylinder can last as little as 10 to 15 minutes in a hostile environment with full exertion,” he advises.
Open-circuit SCBAs are best used in IDLH (immediately dangerous to life or health) situations, such as fire and some hazmat operations, Shipley contends. Lefebvre adds, however, that these SCBAs are sometimes not appropriate for mining operations. “Just going down a shaft underground, sometimes it takes 45 minutes to hit the ground.”
Just how long an SCBA remains in good working order depends largely on the environment in which it is used and how often it is used. Lefebvre says that SCBAs used for “industrial” purposes — which generally do not contain fire-retardant materials — “are really built to last.”
He suggests these should be able to remain in operation between five and 10 years without having to change the entire unit (parts such as cylinders, hoses and the regulator diaphragm can be replaced). If people use a “wall hanger” unit once a year to cle
an a machine, Lefebvre points out, “it will last almost forever.”
That is certainly not the case for firefighters who use the gear often and frequently work in high-heat conditions. In this case, the unit may sometimes not last more than four or five years, he reports.
DROP DOWN, NOT OUT
Lefebvre notes many SCBAs on the market today have a strap that allows users to “drop down” the respirator. In advance of doing so, it is critical that users press the button known as the “first breath activation,” he says. “As soon as you remove your facepiece, automatically the mechanism of the SCBA will detect there’s a leak and it will push [in] air,” he explains. If the button is not pressed, “you are going to empty your bottle in five minutes.”
Clearly, running out of supplied air is life-threatening for any worker — but may be a more frequent concern for firefighters and other emergency responders. Shipley says Sperian expects to launch a display device this summer that shows remaining air in minutes and percentage “based on the air in the cylinder and the breath rate of the user.”
The company has already started to address movement issues for firefighters as well, offering one SCBA product that is equipped with an ergonomic backpack to enhance a user’s mobility by an estimated 25 to 30 per cent. The feature will “greatly reduce the stress placed on the body by lowering the center of gravity of the SCBA.”
FIT FOR SAFETY
But everything needs to fit properly to achieve the maximum protection possible. A key difference between the old and new versions of CSA Z94.4 revolves around qualifications of those conducting respirator fit testing. “That’s been a hot issue recently, making sure people who are doing the fit testing are trained and properly qualified to conduct those tests,” says CSA project manager Ron Meyers.
The new rules update training requirements and examine the possibility of certification for fit testers. Lefebvre, who sits on the standard’s technical committee, characterizes the training section in the 2002 standard as “pretty vague.” The revised version will make clear that “a person who does the fit testing needs to be a proper fit tester,” he says. “Right now, what is happening is [a person is] being trained for 15 minutes with a manufacturer and then he’s claiming he’s been trained.”
The MSA’s Hierbaum says there are two methods to qualify a respirator for use: quantitative and qualitative. The first approach uses a device to measure leakage from a respirator’s facepiece and to sample air inside the respirator; the second approach exposes the wearer to a sweet or bitter chemical. During this test, users don the respirator and report if they can smell the chemicals.
NIOSH currently does not use human subject fit testing to approve a respirator, he says, but this may change next year when a new leakage standard is expected to be released. It will contain protocols similar to the quantitative fit testing method. Lefebvre predicts “it will kill these cheap, disposable masks on the market.”
A MATTER OF MAINTENANCE
Proper fit testing is but one of many considerations when looking to purchase respirators. In many workplaces, says Moldex-Metric’s Dr. Birkner, the presence of multiple gases or particulates demands that an industry professional work with the employer or end-user to get a fix on the best respirator option.
He recommends assessing the situation and the user’s knowledge of respirators, as well as taking into account the maintenance demands. “Do you want something your employees can throw away at the end of the day, do you want it maintained by them or do you have a department that is actually going to be maintaining the respirators?” he asks.
In the case of an SCBA, Shipley recommends having a cache of replacement parts on hand. “I have heard numerous frustrating stories about a simple repair, yet having to wait two, three, four weeks for a simple repair part,” he says.
But remember: replacing parts in a haphazard way — such as putting another manufacturer’s cartridge into the equipment — can be dangerous. “You can’t switch any parts from manufacturer to manufacturer; it negates the certification,” Dr. Birkner cautions.
Hierbaum recommends that buyers take full advantage of product support from a manufacturer, which is likely to include information pertaining to the product itself and when and how to use the respirator. MSA, for example, also offers a “cartridge calculator” that tells a user how long the cartridge will last based on the environment.
Whether work demands call for the use of a full-body hazmat suit and respirator, an SCBA, an APR or an N95, the importance of assessing hazards in a rapidly changing environment should never be underestimated.
Hierbaum cites as an example concerns over the H1N1 virus (swine flu). This can lead to users believing a respirator is an “end-all answer,” he says, when the virus also may be contracted through other body parts, such as the eyes or cuts on the hands.
“So people wear a respirator and think they are automatically protected, but they’re really not,” he cautions. Without properly identifying a hazard, people may “end up with the wrong respiratory protection,” he adds.
With the new CSA Z94.4, says Meyers, the scope of the standard will be expanded to include infectious or biological agents and pathogens. “Probably the part that is taking the most time for us is dealing with infectious agents because you have to deal with it differently in terms of selection of respirators,” he reports.
“With chemicals, you have exposure limits and it is a very defined process. When you are dealing with biologicals, it’s a different approach, so you don’t have exposure limits on many of these types of pathogens.”
Jason Contant is editor of CANADIAN OCCUPATIONAL HEALTH & SAFETY NEWS.