What type of respirator is characterized as negative pressure?

A tight-fitting respirator is characterized as negative pressure because it relies on the user's inhalation to draw air through the filter. This type of respirator creates a seal against the face, which allows for a reduction in pressure inside the mask relative to the outside atmosphere when the user inhales. As a result, contaminated air is drawn through the filter, providing respiratory protection.

Negative pressure respirators, including tight-fitting models, are designed to fit snugly to the face, which ensures that the air entering the respirator is filtered effectively. This is crucial in environments where hazardous airborne particulates, such as lead dust, may be present. Proper fit is essential to maintain this negative pressure condition and ensure that contaminants do not leak around the edges of the respirator.

In contrast, other types of respirators, such as powered air-purifying respirators, operate under positive pressure, where air is actively supplied to the facepiece, helping to maintain a higher pressure inside compared to the external environment. Therefore, it is crucial to understand the function and mechanisms of various respirators in the context of respiratory protection standards.