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A negative pressure room is designed to prevent the cross-contamination of airborne pathogens, radioactive isotopes, gases, volatile organic compounds, and other airborne particles, chemicals, and contaminants that may be injurious to human health.

Where are negative pressure rooms used?

Negative pressure rooms are most commonly used in hospitals to isolate infected patients with contagious diseases such as COVID-19, tuberculosis, SARS-CoV, influenza, measles, chickenpox, and MERS-CoV. They are also used in laboratories, triage areas, pharmacies, clean rooms, research facilities, tissue culture rooms, industrial applications, pharmaceutical compounding rooms, postal and customs inspection facilities, hospital emergency department waiting areas, bathrooms, and other rooms which may house pathogens.

In these infectious areas, room pressure is critical for the safety of the occupant/s and for the entire building. In some cases, a properly functioning negative pressure room is also critical for the safety of the community outside of the building.

Negative pressure rooms are as airtight as possible and allow little to no air in from cracks or gaps like those around windows, light fixtures, and electrical outlets. The only air that enters the room is from a gap under the door (typically ½” high) or from air filters near the floor. The air from the negative pressure room along with its microorganisms, radioactive isotopes, chemical pathogens or other contaminants is typically exhausted through the roof of the building, but depending on the purpose of the room, it may be mechanically filtered or disinfected by UV irradiation or chemicals before being released. 

How do negative pressure rooms work?

Air naturally flows to areas with lower pressure. By maintaining negative pressure (lower pressure) with frequent exhaust, air naturally flows into the room rather than out of the room, decreasing the risk of contamination to adjoining rooms, corridors, and building occupants.

When more air is exhausted from a room than is allowed into it, negative pressure is created, which traps potentially harmful contaminants within the room’s air and prevents them from contaminating adjoining spaces. Specialized construction and climate control equipment are used to build the rooms. Under federal guidelines, a minimum of 12 airflow exchanges per hour must be maintained to sustain a safe environment in the room, but more airflow exchanges may be necessary depending on the room’s size and its purpose.

Components necessary to establish a negative pressure room:

  • HEPA air filters to remove airborne contaminants
  • Self-closing doors
  • 100% outside air ventilation (no return air)
  • Thoroughly sealed floors, doors, ceilings, walls, windows, electrical outlets, lighting fixtures, and wall-mounted equipment
  • Fans and low-level exhaust ducts to direct the air in and out of the room
  • Supply air ducts and exhaust air ducts independent of the building’s air supply system
  • A monitoring system to adjust pressure as needed
  • An intermediate room or anteroom between the negative pressure room and adjoining spaces.
  • Differential air pressure instrumentation panels outside the negative pressure room

Contact Chadwick Service Company to discuss your requirements for a negative pressure room or contamination control.