What does the positive and negative fit check involve?

The positive and negative fit check is an essential respiratory protection protocol that focuses on verifying the fit of a respirator on an individual's face. This process ensures that the mask fits well and adequately covers critical areas, particularly the nose and mouth, to provide a proper seal against asbestos fibers and other hazardous materials.

During a fit check, the wearer perform specific actions to determine if the respirator forms a tight seal. For the positive fit check, the individual exhales gently while covering the exhalation valve. A correct fit would result in a noticeable pressure build-up inside the mask, indicating that air is not escaping through any gaps. For the negative fit check, the person inhales sharply while covering the filters. A proper fit would cause the mask to collapse slightly against the face, again indicating that no air is leaking around the edges.

Achieving a good fit is critical because any gaps can allow airborne contaminants to enter the mask, diminishing its protective purpose. This aligns with the importance of ensuring that the mask fits properly and covers critical areas effectively as stated in the correct response.