In a humid or poorly ventilated or labor-intensive work
environment, using a mask with a breathing valve can help you feel
more comfortable when exhaling. The working principle of the
breathing valve is that the positive pressure of the exhaust gas
during the exhalation blows off the valve sheet to quickly remove
the exhaust gas from the body, reducing the stuffy feeling when
using a mask, and the negative pressure when inhaling will
automatically close the valve to avoid suction Pollutants entering
the external environmen