Negative Pressure Room

By Tabitha Mishra
Last updated: October 6, 2021

What Does Negative Pressure Room Mean?

A negative pressure room is an isolated chamber into which air flows in but does not flow out. It is designed to maintain a lower level of pressure in the room compared to the surrounding environment.

Negative pressure rooms are used in facilities that require infection control, such as in hospitals in inpatient rooms. These rooms prevent infectious germs from spreading through the HVAC system.

Negative pressure rooms are also known as depressurized rooms.

Safeopedia Explains Negative Pressure Room

Negative pressure containment systems are used to protect people and the environment from potentially hazardous molecules, toxins, and drugs. They are considered the ideal choice to minimize the escape of airborne toxins from the isolator and entering a cleanroom environment.

Isolators are physical barriers create a clean working environment by separating a space from its surroundings. The doors and windows in a negative pressure room must be properly sealed.

Negative pressure is maintained from -30 to -20 Pa to prevent particulates from escaping. This is achieved by running the inlet air at 10 to 30% lower than the supplied air.

How Negative Pressure Rooms Work

The negative pressure room works by removing a greater quantity of air from the room than is supplied into it. An active mechanical ventilation system is connected to multiple outlets in the room and it is activated by a pressure sensor that monitors the average room pressure constantly. The air outlets are usually located on the ceiling to drive the flow out of the room so that it does not contaminate the occupants. The room is sealed properly to prevent any leaks.

Pressure Room Features

Both negative and positive pressure cleanrooms require the following:

  • Powerful high-efficiency particulate air (HEPA) filters
  • Automatic doors and well-sealed windows, walls, ceilings, and floors to maintain appropriate air-pressure levels
  • Multiple air changes per hour to maintain air quality and pressure
  • Ante-rooms for changing into personal protective equipment (PPE) and delivering material and equipment
  • In-line pressure monitoring systems

Other Uses of Negative Pressure Rooms

In the healthcare industry, the rooms designed as negative pressure rooms include:

  • Emergency room waiting areas
  • Triage areas
  • Bathrooms
  • Airborne infection isolation (AII) rooms
  • Autopsy rooms
  • Dark rooms
  • Soiled laundry areas
  • Decontaminated spaces

In the pharmaceutical manufacturing industry, negative pressure rooms are also used for biochemical testing. This prevents contaminants from flowing out into other areas. Air that flows out of the room is first filtered to remove any possible contaminants.



depressurized room

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