Fitted particle-filtering masks like N95s are up to 75 times more effective at preventing infection with COVID-19 than surgical masks, according to a study published recently in the Proceedings of the National Academy of Sciences.

This echoes recent recommendations by public health experts about the value of N95 masks, reported by the Wall Street Journal.

It will take 25 hours for an infectious dose of COVID-19 to transmit between people wearing non-fit-tested N95 respirators but if they’re wearing a tightly sealed N95, they’ll have 2,500 hours of protection, per a study reported by the WSJ.

The details: In the recent study by researchers at Max Planck Institute in Germany, they investigated the risk when two individuals are speaking with each other at a close distance. Their study used the most conservative estimates for simulations, meaning that any scenarios with a risk below 1% in their study can be assumed safe in a real-world environment.