What does a positive user seal check for a respirator involve?

A positive user seal check for a respirator involves covering the exhalation port. This procedure is important because it helps ensure that the respirator is properly sealed against the face, allowing the user to create a negative pressure inside the mask. When the user inhales, if the respirator maintains a seal, the mask will collapse slightly towards the face, indicating that air is not leaking around the edges. This check is essential for effective respiratory protection, as any leaks can reduce the effectiveness of the respirator in filtering out harmful particles or gases.

Performing this check by covering the exhalation port mimics the conditions under which the respirator will be used, confirming that it fits correctly and will provide the necessary protection during exposure to hazardous environments. Successful completion of this check is a critical step in ensuring the safety and health of the user when working with herbicides and other chemicals.