Respiratory protection for severe acute respiratory syndrome (SARS)

In March 2003, the World Health Organization issued a global alert on an atypical pneumonia that produced a severe acute respiratory syndrome (SARS). The index SARS case was a doctor from China who was a guest in a Hong Kong hotel. Before the patient’s death, he infected a family member, other hotel guests, and health care workers.1

While more is being learned about SARS, health care workers are working to redefine personnel protective equipment that is appropriate for use with SARS. Standard Universal Precautions (eg, gloves, gowns, surgical masks, and eye shields or glasses to protect the eyes from body fluid splashes) are intended to protect from bloodborne pathogens and do not take into account the possibility of airborne transmission of diseases.

SARS is believed to be caused by a virus from the Coronaviridae family, and the route of transmission is believed to be by droplets or direct inoculation of secretions on the mucous membrane.1 At this time, the World Health Organization2 and the Centers for Disease Control and Prevention3 are recommending that special measures be used to prevent further transmission, including the use of Universal Precautions, N95 particulate respirators, safety glasses, and isolation of select patients.

Particulate respirators

Patients

All suspected SARS patients should be given a surgical mask to reduce droplets that may be introduced into the air. The general population, and particularly SARS patients, are not medically cleared to wear a respirator. If warranted by the history and physical, suspected SARS patients should be placed in isolation with negative pressure airflow for at least 10 days to cover the anticipated incubation period.1

Health care providers

Health care providers are advised to wear a minimum of an N95 particulate respirator when caring for a suspected SARS patient. The Occupational Safety and Health Administration (OSHA) covers health care providers in the United States. OSHA standard 29 CFR 1910.134 requires “written procedures for selecting respirators, medical evaluations, fit testing, use of respirators, maintaining respirators, training, and periodically evaluating the effectiveness of the program.” This discussion will focus on selection, medical evaluation, and fit-testing. Readers are referred to the OSHA Web site for complete information.4

Selecting a respirator

The National Institute for Occupational Safety and Health has developed regulations for certifying nonpowered, air-purifying, particulate-filter respirators.5 Table 1 provides details for classifying N95 particulate respirator filters.

Table 1.

NIOSH criteria for classifying and selecting respirator particulate filters

Filter efficiency	Resistance of filter
95%	N-Not resistant to oil particles
99%	R-Resistant to oil particles
99.97%	P-Oil Proof

Selection of a filter
N-, R-, P-series filters may be used if oil particles are not present in work environment.
N-series filters cannot be used if oil particles are present.
R-series filters can be used if oil particles are present.
P-series filters should be used if oil particles are present and the filter is to be used for more than 1 work shift.

What is an N95 filter?
The N95 particulate filter is 95% effective at filtering out particulates, if there are no oil particles in the particulates.

Medical evaluation

The first medical evaluation and fit-testing takes the longest time and are designed for respirator clearance. OSHA recognizes that respirator use may adversely affect the health of an employee by restricting breathing or cause claustrophobia. The N95 particulate respirator advised for health care workers is a disposable respirator and very light. The medical evaluation may include, but is not limited to, a pulmonary function test, review of symptoms, and assessment by a licensed health care provider. The employee will need to complete information listed in the OHSA Respirator Medical Evaluation Questionnaire (Appendix C to Sec. 1910.134: OSHA Respirator Medical Evaluation Questionnaire).6 Some employees might need help with understanding and filling out the questionnaire.

OSHA further mandates that the evaluation be done during the employee’s work time or a time convenient to the employee. This will require the health care worker to be absent from an assigned work place to fill out the questionnaire, be medically evaluated, have any testing the licensed health care provider deems necessary, and be fit-tested for the respirator. The confidentiality of the employee must be maintained during the evaluation time.

Fit-testing for respirator

Once medical clearance to wear a respirator is obtained, the employee may be fit-tested. Each employee is fit-tested for the appropriate respirator size and is provided training on how to put on, take off and how to clean the respirator. The effectiveness of a respirator will depend on a good mask-to-face seal, and OSHA requires that respirators be checked annually to determine that the fit remains acceptable. During the fitting session, employees are given several respirator options and are allowed to choose the option they prefer on the basis of comfort and adequacy of fit. Room for eye protection, to talk, and the position of the mask on the nose, face, and cheeks determine comfort. The fit of the respirator is determined by proper chin placement, adequate strap tension, fit across the bridge of the nose, ability to cover the distance from nose to chin, tendency to slip, and a seal check.5

Not all employees will be able to wear the N95 particulate disposable respirator; therefore, they may need to be fitted with a powered air-purifying respirator. Employees may only wear the respirators for which they have been medically cleared and fit-tested. The N95 disposable particulate filter respirator should be disposed of after use.

Summary

SARS is a disease that presents multiple challenges. Health care workers need to recognize how to protect against airborne droplets, the uses and limitations of N95 respirators, and the need for careful fitting of respirators to ensure consistent use of personnel protective equipment. A respirator is an important tool used to control SARS but must be incorporated into a total program that also uses patient isolation, Universal Precautions, and protective eyewear to prevent infection of mucous membranes.

Biography

Barbara J. Tobis, RN, COHN-S has 35 years of nursing experience, with the past 21 years in occupational health nursing.