Incorrect use of N95 masks common

Despite the widespread use of N95 masks, only about 12 percent of users may be wearing their masks correctly, according to a study conducted in Singapore.

“These findings support ongoing recommendations against the use of N95 masks by the general public during the COVID-19 pandemic,” noted the researchers. “N95 mask use by the general public may not translate into effective protection but instead provide false reassurance,” they said.

In 2014, the Singapore government distributed N95 masks to households as part of an emergency preparedness programme for haze episodes. The present cross-sectional study was conducted in February 2015 to assess the proficiency of wearing N95 masks. Adults (Singaporean or permanent residents) who lived in Singapore during a period of severe transboundary haze (June–July 2013) were given N95 masks – the same type previously distributed by the government – and accompanying multilingual pictorial instructions. Each participant was asked to put on the mask without being told to refer to the instruction sheet. Assessment of mask-wearing proficiency was determined with a visual mask fit (VMF) test and a user seal check.

A total of 714 households completed the survey. The participants were primarily female (53.5 percent), aged 41–65 years (49.9 percent), and of Chinese ethnicity (72.0 percent).

Only 12.6 percent of participants (n=90) passed the VMF test. Younger participants (adjusted prevalence ratio per 1-year increase in age, 0.95, 95 percent confidence interval [CI], 0.94–0.96) were more likely to pass the VMF test, as were those who had previously received mask fit training (adjusted prevalence ratio, 2.25, 95 percent CI, 1.54–3.30; p<0.001 for both). [JAMA Netw Open 2020;3:e209670]

In contrast, use of the instruction leaflet (adjusted prevalence ratio, 0.75; p=0.27), previous ownership of N95 mask (adjusted prevalence ratio, 1.46; p=0.20), and prior use of mask (adjusted prevalence ratio, 0.80; p=0.39) were not associated with increased likelihood of passing the VMF test.

“The observation that reading pictorial instructions was not associated with increased VMF pass rates may suggest an inherent complexity to N95 mask wearing,” said the researchers.

“Policy measures that encourage mask use in the general public must be coupled with effective training materials beyond instruction leaflets, which our study … found to be inadequate,” they said.

The most common incorrect use of the mask involved strap placement (73.0 percent), a visible gap between mask and skin (61.9 percent), and nose clip tightening (60.4 percent).

Wearing a mask has become the norm during the COVID-19 pandemic. However, evidence on mask-wearing proficiency among the public is lacking. This is of concern as “incorrectly worn masks may not confer effective protection against COVID-19,” the researchers said, suggesting looking into the proficiency of surgical mask use among the general public.