What is the PF assigned to a supplied air half mask continuous respirator?

The assigned protection factor (PF) for a supplied air half mask continuous respirator is 50. This means that when properly fitted and used, the respirator can reduce exposure to airborne contaminants by a factor of at least 50 times the permissible exposure limit (PEL) of the contaminant.

This level of protection is based on the capability of the respirator to provide adequate airflow and a secure fit that minimizes the risk of airborne particles entering the mask. The calculation of PF considers the effectiveness of the respirator in real-world conditions, taking into account potential leaks, user fit, and the maintenance of the equipment.

In the context of this question, a supplied air half mask continuous respirator is typically used in environments where airborne contaminants may exceed safe levels, thus necessitating the use of supplied air to ensure the user has access to breathable air.