How Regulation and Innovation Have Shaped Respiratory Protection

In March 1972, approval criteria for single-use respirators was published in the Federal Register and incorporated as 30 CFR Part 11.8. These criteria allowed single-use respirators to be approved for respiratory protection against pneumoconiosis and fibrosis-producing dusts and mists, including but not limited to aluminum, asbestos, coal, flour, iron ore and free silica. Shortly thereafter, the first approved single-use particulate respirator in the United States was introduced.

In the late 1970s, a filtering facepiece respirator was launched. It featured a valve that allowed the wearer to easily exhale humidity. Previously, the only respirators with a valve were rubber facepieces that required regular cleaning and maintenance.

This new filtering facepiece improved wearer comfort in high heat and humidity conditions — a critical factor in how long respirators are worn on the job. Many workers found filtering facepiece respirators more comfortable than the rubber facepiece that currently were available. In addition, employers appreciated the increased worker acceptance and lack of maintenance.

TECHNOLOGY DRIVES REGULATIONS

Initially, all particulate filtering facepiece respirators met the requirements to be “single-use dust respirators.” As filter technology improved, filtering facepiece respirators could be approved as reuseable filters as well. Filtering facepieces approved to these criteria could be used in a broader range of industries, such as those with exposure to cadmium and lead. Respirator manufacturers also were finding ways to make filter media easier to breathe through.

Another example of technology driving regulations is the development and later requirement for cartridge change schedules. Organic vapor cartridges historically were limited to those vapors having good warning properties and were replaced when the respirator wearer detected, or smelled, the vapor. Then a predictive model was developed to determine the service life of cartridges for organic vapors.

OSHA later accepted this concept, which encouraged manufacturers to provide a method to calculate cartridge service life. This resulted in an OSHA-required change schedule in the workplace and expanded air-purifying respirators use to organic vapors with poor warning properties. A key manufacturer developed the first user-friendly version to help employers easily determine cartridge service life.

The filter efficiency tests for particulate respirators were published in the mid-1950s using test equipment available at that time. Each test was lengthy and by the 1990s, it was recognized that new testing technology and new applications existed and that the respirator approval criteria could be updated.

REGULATIONS DRIVE TECHNOLOGY

In 1994, NIOSH published new respirator regulations — 42 CFR 84 — that incorporated new particulate filtration tests. These tests created nine classes of particulate filter approval with minimum efficiency levels ranging from 95 percent to 99.97 percent efficiency against a very demanding particle size of approximately 0.3 micron mass median aerodynamic diameter (MMAD) particles. Silica was replaced by sodium chloride (for N-series respirators) and an oily aerosol [dioctyl phthalate (DOP)] (for R- and P-series respirators) as the test aerosols.

These new regulations posed a challenge to several leading manufacturers because the filter media used in many of their 30 CFR Part 11 respirators wouldn't meet parts of the new NIOSH standard without increasing the amount of filter media utilized. This could result in a less comfortable respirator. In addition, the oily mist test aerosol was especially challenging for some filter media.

MELT-BLOWN FIBERS

Respirator manufacturers were looking for ways to create respirators that had the lowest breathing resistance (for comfort) and still meet the new respirator regulations. Based on technology developed in the 1950s in the U.S. Naval Research Laboratory, developers knew that filter media made from melt-blown polymer fibers was excellent at retaining an electrostatic charge — and was more consistent and permanent than resin wool.

In the 1970s, manufacturers were using electrostatically charged polymer fibers for filter media to increase filter efficiency. Using less filter media allowed respirators to be lighter and more comfortable. This is important, because proper fit and comfort are key factors in whether respirators are worn and for how long. Wearing a respirator the entire time a worker is in a contaminated area is essential to reducing their exposure to hazardous airborne substances.

Over the years, scientists have made many advances to enhance the electrostatic charge and prolong the charge on fibers. They also learned to incorporate carbon particles into the non-woven media, thereby helping reduce nuisance levels of gases and vapors.

During the 1990s, scientists developed better polymers and new charging processes for fibers. In addition, additives were incorporated that reduced the effect of oily mist on charged fibers.

As the pressure drop of filter media was decreased, exhalation valves changed as well. Researchers developed an ingenious new valve for respirators. The innovative shape opens very easily during exhalation. An easy-opening valve allows hot air and humidity to escape from the respirator more efficiently and improves user comfort.

Previously, many people believed it was impossible to create a valve that could open under such low pressure. The scientists proved skeptics wrong — and the valve design now is protected by eight U.S. patents. The overall result of the 42 CFR 84 regulations was development of new respirators featuring enhanced comfort features and updated designs that met the new testing requirements.

FUTURE CHALLENGES

Some developing countries do not have respirator performance or use standards. Through increasing awareness of occupational health and safety issues among employers, workers and governments, respirator regulations will be strengthened and adopted. The International Standards Organization (ISO) currently is developing global respirator performance standards that will be available for all countries to incorporate into their respirator use regulations.

These new performance standards may again pose a challenge to respirator manufacturers and may drive new technologies. In addition, as the population of respirator users expands, respiratory product developers will need to consider designing respirators for an even wider variety of faces.

While engineering controls always are the first choice to eliminate or reduce a hazard, respiratory protection has been in use for years and will continue into the future. Health and safety professionals working together with agencies such as NIOSH and OSHA, and with international organizations such as ISO, will continue to promote the development of new respirator technology, designs and both performance and use regulations to help protect workers around the world.

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Bill Herris, global brand manager, 3M Occupational Health and Environmental Safety Division, has worked in various capacities in the respiratory protection business for over 39 years.