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Pediatric face masks ineffective against submicron aerosols
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Face masks designed for use by children appear to have a high rate of intrinsic penetration at the submicron size range, suggesting that these masks do not provide adequate protection from public health threats involving bioaerosols, according to recent findings.
In the study, researchers selected three brands of available pediatric face masks that were available for convenient ordering, referred to as P1, P2 and P3. These were compared with two brands of previously studied N95 adult respirators, which were again investigated using the established protocol and labeled as brands A1 and A2. The facemasks were exposed to neutralized, polydispersed sodium chloride aerosols, with intrinsic penetration measured at different flow rates in the submicron size range.
The researchers found that of the adult respirators, A1 had a maximum penetration of significantly less than 5% at a flow rate of 10 L/min, and a maximum penetration equal to or slightly exceeding 5% at the highest flow rate of 70 L/min. A2 had significantly lower penetration compared to A1, even at 70 L/min.
In the analysis of the children’s masks, however, the researchers found that there was significant penetration variability between brands at the highest flow rates. While P1 demonstrated a maximum penetration of >5% at flow rates of 5 mL/min and 10 L/min, the maximum particle penetration size (MPPS) for P1 was variable within the 40 nm to 70 nm size range at all flow rates. P2 and P3 were distinct from P1 in that their penetration rates were markedly higher, and also because the MPPS for these ranged from 100 nm to the largest size limit studied, 710 nm, at different flow rates. In an analysis involving isopropanol-dipped respirators and facemasks, the researchers found that although P1 and P2 appeared to have at least one layer of protective electret fibers to decrease penetration, P3 likely has no electret fiber layers.
The researchers wrote that although low penetration is a priority for face masks, comfort is also a key factor to ensure pediatric compliance. They indicated that the ongoing threat of airborne diseases calls for additional research into pediatric face masks.
“Besides using electret filters, developing facemasks meant for specific anthropometric features of children is a possible alternative for increasing the level of protection,” they wrote. “Indeed, respirators when donned based on anthropometric features even without fit-testing have led to better protection compared to ad-hoc respirator donning.”
Disclosure: The researchers report no relevant disclosures.
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