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What is BFE and Delta P?

The Bacterial Filtration Efficiency (BFE) test calculates the percentage of bacteria that is filtered out by the mask. Essentially, it tests the mask’s ability to prevent bacteria from passing through. A higher BFE means the mask is filtering out more of the bacteria in the air. The PRO mask has an average BFE of 99.72%.

To test the BFE, a known amount of bacteria is suspended in a mixture of air to mimic real-life conditions. The mixture of air and bacteria is pulled through the mask at a constant rate for a minimum of four hours.

Due to the small size of the individual bacterium and their tendency to group together, colony-forming units (CFU) are counted instead. CFUs are tiny clumps of bacteria that can consist of two or more individual bacterium. The CFUs that passed through the mask are counted and then the BFE can be calculated by dividing the downstream CFU quantity by the initial quantity used in the air mixture.

Differential Pressure (Delta P) is tested to determine the breathability of the mask. This test ensures the mask is still easy to breath in and out of after filtering out bacteria in the air. Delta P compares the force of breathing in with the force of breathing out. The PRO mask met all manufacturing standards in compliance with quality regulations in regards to Delta P.

If you have further question, please contact us by email at or Chat button on our sites to connect with our Customer Service Team.