Definition - What does negative pressure respirator mean?
A negative pressure respirator is a breathing device that is placed over the face so that contaminants cannot get into the airway. The mask must fit properly so there is no possibility of leakage. The device is called negative pressure because during inhalation the pressure inside the mask is negative (lower than) the outside positive air pressure. During inhalation, air is pulled through a filter device.
SureHire explains negative pressure respirator
Many negative pressure respirators are classified as mechanical filter respirators because they use disposable filters. The HEPA filter is most widely known and can reduce the intake of harmful particles up to 99.97% of the time and as small as 0.3 micrometers in diameter or smaller.
Because air pressure outside the mask is higher than inside the mask, any seal leak or improper fit will pull in air and expose workers to potential hazards.
An employer should ensure that the masks provided to employees have been fit-tested for quality control.
