Why is the ventilation valve of the mask inclined?

The ventilation valve of the mask is inclined at a certain angle to avoid air leakage when breathing.

If the ventilation valve is straight, the airflow rushes directly to the valve when exhaling, which is more likely to cause airflow dispersion and lead to air leakage. Inclined valve can better avoid the direct impact of air flow, let the air flow out slowly along the valve when exhaling, and reduce the probability of air leakage.

In addition, the inclined valve can better adapt to the shapes and sizes of different faces, make the mask more compact and improve the filtering effect.