What type of respirator may not provide an adequate seal when worn with facial hair?

Tight fitting respirators are designed to create a secure seal around the face to ensure that contaminants do not bypass the respirator and are instead filtered out before the wearer inhales. However, the effectiveness of this seal is significantly compromised when the wearer has facial hair. Hair can create gaps between the respirator's sealing surface and the skin, allowing unfiltered air to enter and potentially exposing the wearer to harmful substances.

In contrast, half-mask and full-face respirators can also have issues with sealing if not properly fitted, but the critical factor here is the "tight fitting" aspect, which emphasizes the importance of having a clean-shaven face for optimal performance. Loose fitting respirators, such as those designed for non-hazardous environments, do not rely on a tight seal and therefore are not affected by facial hair in the same way, making them less reliant on facial contours for proper function.