COVID-19 Forced Hospitals to Build Negative Pressure Rooms Fast


A portable anteroom can be used as an extra layer of protection between the isolation space and the rest of the hospital. A positively pressured anteroom, for instance, lets staff don PPE in a protected environment.  

During the Middle Ages, people tried to escape the plague by sequestering themselves-not an easy task (then or now). Dealing with infectious diseases still comes down to containing the spread. 

Modern hospitals have isolation down to a science, literally. Nowadays, it means having a room or unit in which the infected air is rerouted, away from other patients and hospital staff. One way to do this is with a negative pressure room, in which a lower air pressure allows outside air into the room; any air that flows out of the room has to pass through a filter. By contrast, a positive pressure room maintains a higher pressure inside the treated area than that outside it. Clean filtered air is pumped in; if there’s a leak, the air is forced out of the room. Positive pressure rooms are usually used for patients with compromised immune systems; negative pressure rooms are common in infection control, to ensure infectious germs don’t spread via the heating, ventilation, and air conditioning (HVAC) system. 

A negative pressure room is particularly crucial when something like coronavirus disease 2019 (COVID-19) strikes-this new virulent killer is too much of an unknown quantity to take even the smallest chances of spreading. But the need for such rooms can put extreme stress on hospitals, which are not always ready to handle influxes of infected patients-let alone in the massive numbers of the COVID-19 pandemic. In New York, the current epicenter of the pandemic, total cases crested to 75,000 in early April-and the peak hadn’t even been reached yet.

In the case of a pandemic, says Nick Clements, PhD, an investigator at the University of Colorado, Boulder, wrote in a 2014 blog post, hospitals should be prepared for at least a 300% to 500% increase in ICU and isolation room capacity.1 But despite the increasing need for negative pressure rooms, Saskia Popescu, PhD, MPH, MA, CIC, and a member of Infection Control Today®’s Editorial Advisory Board, says most hospitals are not equipped to handle the high volumes of patients requiring them. Popescu, a hospital epidemiologist and infection preventionist, has researched the role of infection prevention in facilitating global health security efforts. 

“Hospital ventilation systems are designed and engineered to handle a handful of these rooms per unit,” she wrote in a 2017 article, “and so response plans often include moving these patients to designated areas like gymnasiums or tented-care areas built in parking lots.” 2

Most hospitals, small and large, have some form of negative pressure space. But a pandemic with a fast-spreading mystery virus has meant many facilities are having to come up-quickly-with more places to keep the COVID patients safely isolated. Some, like Humber River Hospital, in Toronto, built in 2015 with “SARS foremost in our mind,” according to president and CEO Barbara Collins, are purpose-built to be “pandemic safe.” She told Toronto’s The Star  that her hospital is capable of isolating entire departments under negative pressure. Moreover, the ambulance bay and an adjoining “hazmat room” are tailored for “seamless transformation” into a pandemic-ready area.3

In an interview with WCMH-TV, Jo Henman, director of infection prevention at OhioHealth, in Columbus, said her facility has 85 inpatient negative-pressure rooms and, thanks to portable high-efficiency particulate air (HEPA) filters, the ability to create more if needed.4

At Westchester Medical Center, an 895-bed regional system in the New York metropolitan catchment area, every ICU is negative pressure, and can swap out as needed (except with oncology and other high-risk patients, of course). Minnesota-based Alomere Health, which estimates its surge volume at 20 COVID-19 patients at full capacity, plans to use its negative pressure medical/surgical rooms if the ICUs overflow.5  

The 1500-bed Cleveland Clinic has converted a 4-story health education building into a surge hospital, with 327 beds for low-acuity patients who don’t need ventilators and accommodating up to 1000 hospital beds if needed.6 California spent $30 million to lease short-term space.7 In late March, Detroit and Chicago were both planning to turn convention centers into temporary COVID-19 hospitals.7

Or, a hospital might, like Brigham & Women’s Faulkner Hospital in Boston, just decide to do a large-scale conversion-in double-quick time.8 Faulkner rapidly transformed 2 negative pressure wards for COVID-19 patients. The initial plan went from concept to development within just a few days, with a project that included converting the existing HVAC systems to 100% outside air to eliminate the risk of recirculated air, revising the system controls by rewriting its code, and rebalancing the air distribution components.

Older hospitals, or those with budgets that won’t support major conversions, can still prepare quickly. The American Society for Health Care Engineers says that standard patient rooms can be retrofitted as negative pressure isolation rooms.9 The American Society of Heating, Refrigerating and Air-Conditioning Engineers’ Standard allows for using recirculated room air, provided the air first passes through a HEPA filter. This can be accomplished with a recirculating HEPA filter unit, the association says. 

In a real time-crunch, a temporary isolation area can be set up surprisingly fast. Investigators from University of Colorado, Boulder and the VA’s National Center for Occupational Health and Infection Control got a temporary 30-bed negative pressure ward up and running in less than an hour.10  

They tested it in a fully functioning hospital in the San Francisco Bay Area. The existing ward had its own dedicated air-handling unit, dedicated bathroom exhaust system, a separate dedicated exhaust system for return registers in the isolation rooms, and a firewall separating the ward from the rest of the hospital. 

The research team used 2 heating, ventilation, air conditioning HEPA-filtered negative-air machines to establish the pressure. Performing pressure measurements at 22 locations, they found they maintained negative pressure that was actually higher than recommendations by the US Centers for Disease Control and Prevention (CDC), and there was no pressure reversal when medical staff entered or exited. They did find that some rooms became neutrally or slightly positively pressured, so they advise staff to use personal protective equipment at all times.

The infection prevention and control team “was heavily involved and present at every meeting,” hospital administration was very supportive, and the nursing staff were especially interested and engaged, Shelly Miller, PhD, the team leader, says.

And the research team proved that it could all be done in approximately 40 minutes-including installation and troubleshooting of the anteroom. “We wanted to get it up fast, it was duct tape and plastic,” says Miller.

Their solution could be lifesaving for smaller or rural hospitals. Miller points out that according to the Institute of Medicine’s report on medical surge capacity, the cost of pandemic preparedness is important to consider-tents, temporary housing materials, disaster response trailers, and HEPA-filtered negative-air machines are expensive. In their study, choices such as plastic sheeting with zippered openings helped lower costs.

A portable anteroom can be used as an extra layer of protection between the isolation space and the rest of the hospital. A positively pressured anteroom, for instance, lets staff don PPE in a protected environment. A drawback is that because the anteroom is less pressurized than the isolation room, there’s a risk of infectious particles carrying from the movements of healthcare workers into the patient’s room.  

Further, because the pressure in these specialized rooms has to be so carefully nuanced, maintenance is important. Citing a 2001 long-term assessment of isolation room performance, Nick Clements notes in his blog post that isolation room operating conditions may “shift away from optimal” for a variety of reasons, and operating conditions are “somewhat temporally variable.”1 A loose air handling unit fan-belt or accidental changes made during maintenance could, he says, result in “sharp changes” in the room pressure.

There are few studies as yet testing the effectiveness of establishing temporary isolation wards during a surge, cautions Clements, who was on the team that established the Bay Area temporary ward. Before including a temporary isolation ward in a hospital surge capacity plan, he advises conducting a (successful) full-scale demonstration to uncover any logistical and engineering issues.

Caring for patients in negative pressure rooms can amplify the usual constraints and stresses for staff. Guangdong Second Provincial General Hospital, in China, came up with a way to help lessen some of the stress.11

By February 2020, the hospital had admitted more than 30 confirmed cases of COVID-19 and more than 200 suspected cases. It’s not uncommon, clinicians from the hospital report in The Lancet,11 that medical personnel in negative pressure wards are not fully aware of their exposure while caring for patients. So, the hospital set up an innovative infection-control system called the observing system. Cameras cover the entire ward except for the privacy area. Infection control observers, who are appointed by the hospital’s Department of Infection Control and Nursing and undergo intensive training to become familiar with the requirements for infection control in the negative pressure wards, monitor the wards via computers. 

Their responsibilities include maintaining the normal operation of the isolation wards, supervising the implementation of disinfection, ensuring a sufficient supply of protective materials, arranging specimens for inspection and-not least-they “relieve anxiety of the medical personnel while treating patients.” 

They also watch to make sure healthcare providers don’t omit or overlook steps in putting on or taking off PPE. In one case a patient’s zipper unexpectedly ripped a nurse’s glove. Discovering the situation, the observer “immediately soothed the nurse and sent another staff member into the ward to assist,” assessed the risk for the nurse, and arranged a quarantine room to ensure full safety before the nurse returned to the ward.

The frontline medical staff highly recommend the new system, the authors say. 

Whether caring for a few or thousands of infectious patients, healthcare facilities must be both proactive and flexible. Most recently, Miller and her team have been conducting another pop-up test, this one in a nursing home, depressurizing an entire wing. Given that nursing homes have all along been hotspots of COVID-19, fast, secure response is key. Until we know more about this deadly intruder, protection is the strongest weapon.


Janet Dyer is a writer and editor specializing in clinical topics. She lives in Suffern, NY.



1.     Clements N. Temporary isolation rooms and their application to hospital surge capacity for infection control. microBEnet. 10-04-2014. Accessed 04-26-20.

2.     Popescu S. Building airborne isolation units during emergent times. ContagionLive. 08-25-17. Accessed 04-26-20.

3.     Miller J. How ‘negative pressure rooms’ can help hospitals fight the coronavirus. The Star. 01-31-20. Accessed 04-26-20.

4.     Hart T. Hospitals prepare ‘negative-pressure rooms’ for COVID-19 patients. WCMH. 03-09-20. Accessed 04-26-20.

5.     Oliver E. Minnesota health system releases surge plan. Alexandria Echo Press. 04-13-20. Accessed 04-26-20.

6.     Paavola A. Cleveland Clinic builds COVID-19 surge hospital. Becker’s Hospital Review. 04-17-20. Accessed 04-26-20.

7.     Paavola A. The race to boost hospital bed capacity: updates from 5 states. Becker’s Hospital Review. 03-30-20. Accessed 04-26-20.

8.     Brigham & Women’s Faulkner Hospital: negative pressure wards for COVID-19 treatment. Fitzemeyer & Tocci. 04-07-20. Accessed 04-26-20.

9.     Herrick M. Retrofitting an existing room for negative isolation. ASHE Health Facilities Management. 02-01-17. Accessed 04-26-20.

10.  Miller SL, Clements N, Elliott SA, Subhash SS, Eagan A, Radonovich LJ. Implementing a negative-pressure isolation ward for a surge in airborne infectious patients. Am J Infect Control 2017 45:652-9. Accessed 04-26-20.

11.  Chen X, Tian J, Li G, Li G. Initiation of a new infection control system for the COVID-19 outbreak. Lancet Infect Dis 2020 20(4):397-398. Accessed 04-26-20.

Related Videos
Anne Meneghetti, MD, speaking with Infection Control Today
Vaccine conspiracy theory vector illustration word cloud  (Adobe Stock 460719898 by Colored Lights)
Infection Control Today's topic of the month: Mental Health
Infection Control Today Topic of the Month: Mental Health
NFID Medical Director, Robert H. Hopkins, Jr., MD  (Photo courtesy by Evoke Kyne)
An eye instrument holding an intraocular lens for cataract surgery. How to clean and sterilize it appropriately?   (Adobe Stock 417326809By Mohammed)
Paper with words antimicrobial resistance (AMR) and glasses.   (Adobe Stock 126570978 by Vitalii Vodolazskyi)
 MIS-C (Adobe Stock 350657530 by Bernard Chantal)
Medical investigators going over data. (AdobeStock 589197902 by Wasan)
Related Content