By Leslie Canham, CDA, RDA
With the rapid spread of novel influenza A (H1N1) — swine flu — concerns about respiratory protection seem to be on everyone’s mind. On Aug. 5, 2009, the Centers for Disease Control and Prevention (CDC) issued interim recommendations for face mask and respirator use to reduce novel influenza A (H1N1) virus transmission. This article will focus on the different types and classifications of masks, different levels of protection, and how to choose a mask.
CDC is preparing for a possibly severe influenza season. Because both seasonal flu and H1N1 may spread at the same time, it is possible that a lot more people will get sick this season than normally do during a regular flu season. There also may be more people hospitalized and more deaths this season than during a normal flu season.1
How should dental offices prepare for flu season?
In a previous issue of Dental Assisting Digest™, the article “How’s infection control in the reception room?” included information on how to prepare your office for flu season. One way to prepare is to follow the OSHA requirement for use of appropriate protective attire, which includes wearing a surgical face mask.
How do face masks protect us?
The purpose of wearing a surgical mask is twofold. First, the mask protects the patient against microorganisms generated by the dental health-care provider (with >95% bacterial filtration efficiency). Secondly, the mask protects the dental health-care provider from large-particle droplet spatter that might contain bloodborne pathogens or other infectious microorganisms.
Different types of face masks vs. respirators
Face masks — Unless otherwise specified, the term “face masks” refers to disposable face masks cleared by the U.S. Food and Drug Administration (FDA) for use as medical devices. This includes face masks labeled as surgical, dental, medical procedure, isolation, or laser masks. Such face masks have several designs.
Respirators — "Respirator" refers to an N95 or higher filtering face piece respirator certified by the CDC/National Institute for Occupational Safety and Health (NIOSH). A respirator is designed to protect the person wearing the respirator against breathing in very small particle aerosols that may contain viruses. A respirator that fits snugly on the face can filter out virus-containing, small-particle aerosols that can be generated by an infected person, but compared with a face mask it is harder to breathe through a respirator for long periods of time. Respirators are not recommended for children or people who have facial hair.
When respiratory protection is required in an occupational setting, respirators must be used in the context of a comprehensive respiratory protection program as required under OSHA’s Respiratory Protection standard (29 CFR 1910.134). This includes fit testing, medical evaluation, and training of the worker. When required in the occupational setting, people with facial hair that interferes with the face seal cannot use tight-fitting respirators.
When respirators are used on a voluntary basis in an occupational setting, requirements for voluntary use of respirators in work sites can be found on the OSHA Web site.2
Different levels of protection
The American Society for Testing and Materials (ASTM) evaluates masks according to five performance factors:
- Fluid resistance
- Bacterial filtration efficiency
- Particulate filtration efficiency
- Differential pressure/breathability
- Flammability
Fluid resistance is the ability of the mask to prevent fluid from passing though it to the wearer’s face. Bacterial filtration efficiency measures the size of bacterial cells that could pass through the mask to the wearer. Particulate filtration measures the efficiency of the masks to filter particles. Differential pressure/breathability measures the air pressure both inside and outside the mask. Flammability measures how easily the mask can be ignited and burn.
How to choose a mask
Choosing a mask depends on the type of procedure and level of contamination anticipated. When performing procedures that generate high levels of aerosolized moisture such as use of high-speed handpieces, air-water syringes, and ultrasonic scalers, an ASTM “high barrier” category mask should be used.
For procedures with a low level of aerosolized moisture or particles, an ASTM “moderate barrier” mask can be used. For procedures with no aerosolized moisture or particles, such as oral exams or taking X-rays, an ASTM “low or primary barrier” mask can be used.
Non-ASTM masks do not meet the ASTM performance standards. These non-rated masks provide only a paper barrier as protection. Because non-rated ASTM masks offer the lowest level of protection for the wearer, they should not be worn for dental procedures where aerosolized moisture or particles are generated from the patient’s oral cavity or when working with items contaminated with oral fluids.
Armed with information on mask selection, we can take steps to protect ourselves from getting an infection.
References
1 Novel H1N1 Flu: CDC Response. Centers for Disease Control and Prevention. Aug. 19, 2009. Web. Sept. 4, 2009. http://www.cdc.gov/h1n1flu/cdcresponse.htm.
2 Interim Recommendations for Facemask and Respirator Use to Reduce Novel Influenza A (H1N1) Virus Transmission. Centers for Disease Control and Prevention. Aug. 5, 2009. Web. Sept. 3, 2009. http://www.cdc.gov/h1n1flu/masks.htm.
