Over 3 million United States employees in approximately 1.3 million workplaces are required to wear respiratory protection. The Occupational Safety and Health Administration (OSHA) (29 CFR 1910.134) requires an annual fit test to confirm the fit of any respirator that forms a tight seal on the wearer’s face before it is used in the workplace.1 Once a fit test has been done to determine the best respirator model and size for a particular user, a user seal check should be done every time the respirator is to be worn to ensure an adequate seal is achieved.
What is a User Seal Check?
A user seal check is a procedure conducted by the respirator wearer to determine if the respirator is being correctly worn. The user seal check can either be a positive pressure or negative pressure check. During a positive pressure user seal check, the respirator user gently exhales while blocking the paths for air to exit the facepiece. A successful check is when the facepiece is slightly pressurized before increased pressure causes outward leakage. During a negative pressure user seal check, the respirator user sharply inhales while blocking the paths for air to enter the facepiece. A successful check is when the facepiece collapses slightly under the negative pressure that is created with this procedure.
A user seal check is sometimes referred to as a fit check. A user seal check should be completed each time the respirator is donned (put on). It is only applicable when a respirator has already been successfully fit tested on the individual.
How do I do a User Seal Check while Wearing a Filtering Facepiece Respirator?
Not every respirator can be checked using both positive and negative pressure. Refer to the manufacturer’s instructions for conducting user seal checks on any specific respirator. This information can be found on the box or individual respirator packaging. The following positive and negative user seal check procedures for filtering facepiece respirators are provided as examples of how to perform these procedures.
How to do a positive pressure user seal check
Once the particulate respirator is adequately donned, place your hands over the facepiece, covering as much surface area as possible and exhale gently into the facepiece. The face fit is considered satisfactory if a slight positive pressure is being built up inside the facepiece without any evidence of outward leakage of air at the seal. Examples of such evidence would be the feeling of air movement on your face along the seal of the facepiece, fogging of your glasses, or a lack of pressure being built up inside the facepiece. If the particulate respirator has an exhalation valve, then performing a positive pressure check may be impossible. In such cases, a negative pressure check should be performed.
How to do a negative pressure user seal check
Negative pressure seal checks are typically conducted on particulate respirators that have exhalation valves. To perform a negative pressure user seal check, cover the filter surface with your hands as much as possible and then inhale. The facepiece should collapse on your face, and you should not feel air passing between your face and the facepiece. In the case of either type of seal check, if air leaks around the nose, use both hands to readjust the nosepiece by placing your fingertips at the top of the metal nose clip. Slide your fingertips down both sides of the metal strip to more efficiently mold the nose area to the shape of your nose. Readjust the straps along the sides of your head until a proper seal is achieved.2
If you cannot achieve an adequate seal due to air leakage, you may need to be fit tested for a different respirator model or size.
Can a user seal check be considered a substitute for fit testing?
No. The user seal check does not have the sensitivity and specificity to replace either fit test methods, qualitative or quantitative, that is accepted by OSHA (29 CFR 1910.134). A user should only wear respirator models with which they have achieved a successful fit test within the last year. NIOSH data suggests that the added care from performing a user seal check leads to higher quality donning (e.g., reduces the chances of a donning with a poor fit).3
Where can I Find More Information?
This information and more is available on the NIOSH Respirator Trusted-Source webpage.
CLICK HERE for the NIOSH pdf
References
1. OSHA [1998]. Respiratory Protection. 29 CFR 1910.134. Final rule. Fed Regist 63:1152-1300.
2. NIOSH [2010]. How to properly put on and take off a disposable respirator. U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Insitute for Occupational Safety and Health, DHHS (NIOSH) Publication No. 2010-133 https://www.cdc.gov/niosh/docs/2010-133/pdfs/2010-133.pdf
3. Viscusi DJ, Bergman MS, Zhuang Z, and Shaffer RE [2012]. Evaluation of the benefits of the user seal check on N95 filtering facepiece respirator fit. J Occup and Evironl Hyg. 9(6):408-416.
Photos courtesy of NIOSH