The resistance of the KN95 mask to inhalation is relatively large, and it will feel very uncomfortable for a long time to wear. A mask equipped with an exhalation valve closes the valve when inhaling, air is filtered into the airway through the mask, and the valve opens when exhaling, and exhaled gas is discharged into the air through the valve to make breathing easier. KN95 masks with valves are useful. Can filter 95% of tiny particles (0.3 microns in diameter) in the air.
The KN95 respirator with exhalation valve does provide the wearer with the same level of protection as without the valve. The presence of an exhalation valve reduces the resistance to exhalation and makes breathing (exhalation) easier.
However, in situations where a sterile area must be maintained (for example, when performing invasive surgery in the operating room or operating room), a respirator with an exhalation valve should not be used because it allows unfiltered exhaled air to enter Bacterial area. .
In addition, patients who have been infected with new coronavirus should not wear a mask with a mask.