Safe to fit test N95 masks every 3 years instead of annually, study finds
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Key takeaways:
- Nearly 100% of N95 masks pass fit tests after 3 years, suggesting annual tests are not necessary.
- Moving to 3-year test cycles could save as much as $400 million per year.
Findings from a new study suggest that fit tests for N95 masks can safely be done every 3 years instead of every year, researchers reported.
The CDC recommends fit testing at least annually to ensure respirators properly fit and seal against the wearers’ face, and that fit testing be repeated when a health care worker begins using a new model or brand.
In the new study, Thomas C.S. Martin, BMBCh, MA, an assistant clinical professor of medicine at the University of California, San Diego, and colleagues found that almost 100% of masks passed fit tests after 3 years and would likely pass at the same rate after 5 years.
“Our results call into question the rationale behind the mandated annual fit testing for N95 respirators, which was based on one small study of 229 participants,” Martin and colleagues wrote in Infection Control & Hospital Epidemiology.
That 2016 study predicted fit test failure would increase from 10% after 1 year to 25% after 3 years based on data collected in the late 1980s and 1990s on hospital transmission of tuberculosis, according to the researchers.
During the COVID-19 pandemic, findings from studies on N95 mask efficacy, proper fit and potential reuse suggested they could safely be reprocessed but that fit remained a major concern, Martin and colleagues wrote.
Experts also repeatedly have said since the emergence of SARS-CoV-2 that, in addition to wearing a mask that has been shown to protect against pathogens, a proper mask fit that seals against the face is key for protection.
Martin and colleagues analyzed data on 15,757 health care workers who underwent at least two or more annual respiratory fit tests in the University of California, San Diego Health system.
All fit tests were performed on one of five respirators, with participants required to have recorded a pass on a mask with at least one subsequent test of the same mask. Masks with a pass and a fail within 3 months were considered a fail.
The researchers then performed a Kaplan-Meier survival analysis to estimate fit test failure at 3 and 5 years after a pass on the same mask.
Among 49,290 fit test results, 98.6% were passes, 0.7% were fails and 0.7% of tests were not completed. Of the 352 fit tests that were not completed, 338 were due to presence of a beard, five were due to allergies, two were due to claustrophobia and seven were due to reasons unrelated to the mask, according to the study. Overall, the researchers identified 55 instances of failure after a previous fit-test pass.
According to the survival analysis, which included 12,065 people, 54 events were recorded after 3 years — equal to a 99.4% probability of passing a fit test after that much time. The 5-year probability of passing a test, though based on fewer data, was also 99.4%.
Additionally, Martin and colleagues noted the “substantial” cost of maintaining equipment, full-time staff and physical infrastructure to perform annual testing across the United States, estimating it to fall between $200 million and $400 million per year. On top of this, they noted that the 30 to 60 minutes per year each person has to dedicate to testing also carries a cost.
“We have demonstrated that N95 respirator fit test failure after a previous pass within 3 years is rare,” Martin and colleagues wrote. “Our results support a change in policy to reduce the fit testing interval mandate from annual to every 3 years.”
References:
- Martin TCS, et al. Infect Control Hosp Epideol. 2023;doi:10.1017/ice.2023.187.
- Zhuang Z, et al. J Occup Environ Hyg. 2016;doi:10.1080/15459624.2015.1116692.
- CDC. The National Personal Protective Technology Laboratory: Fit Test FAQs. https://www.cdc.gov/niosh/npptl/topics/respirators/disp_part/respsource3fittest.html. Last reviewed Sept. 3, 2021. Accessed Sept. 7, 2023.
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