As the COVID-19 pandemic has swept the world, it has threatened to overwhelm healthcare facilities with a surge of critically ill patients. But there is another, more profound impact: it has changed the relationship between patients and caregivers, and raised questions about hospitals’ safety both as places to seek help and places to work.  

Infection prevention and control has always been a key priority in modern healthcare, but it was focused primarily on protecting patients from diseases in the hospital environment and controlling drug-resistant “superbugs”. With COVID-19, everyone is a potential victim and everyone – no matter how healthy they may appear – a potential carrier. We cannot afford to close hospitals and it is not sustainable to run them at lower capacity for extended periods of time. Instead, we have to find ways to keep them functioning safely and efficiently while there is a higher level of infectious disease circulating among the population – in the certainty that COVID-19 will not be the last pandemic we face, and that the next one may not be transmitted in the same way. This will involve rethinking everything from how hospital workers are protected, to the way that hospital environments are engineered.

“On one level, you could argue that the hospital is no different to any other part of the environment in which we are trying to understand how to protect people from each other. But it’s particularly important because you’ve got a concentration of the sickest people, and you have healthcare workers exposed to levels of COVID that most of us wouldn’t see outside of our own household,” says Professor John Clarkson, director of the Engineering Design Centre at the University of Cambridge, a member of its infectious diseases research centre and an expert advisor to the UK’s government’s COVID-19 winter planning report. “Because of what we know about COVID, we have to revisit everything we do in a hospital, and every interaction we have. It changes the whole way you look at the world.”

In the immediate response to COVID-19, there has been much activity and concern around the world about securing adequate amounts of personal protective equipment (PPE) to protect frontline healthcare workers. Since the start of the pandemic, Clarkson has been working with surgical teams at Addenbrookes teaching hospital in Cambridge to understand their experiences of wearing face masks, and ultimately to develop better models: “You want the right mask for the right person at the right time for the right procedure, and that could be very wide-ranging.” Most PPE is not designed for healthcare, and not for protection from viruses. Clarkson’s project involves detailed feedback with medical teams but also using imaging equipment to capture face shapes. “Are they all utterly unique, or can they be clustered in some way so that you could have a wider set of standard masks that would fit more people, more like shoe sizes? Where that’s not possible, can we print an element of the mask that sits around the face that is uniquely shaped for the individual, to accommodate the movement they need?”

Clarkson takes a “systems thinking” approach to healthcare improvement, which seeks to gain a deep understanding of the context of a problem before trying to solve it. Through this lens, the protection problem becomes a proxy for much wider challenges, he says, intrinsically linked to the physical environment, its layout and ventilation, and how people move through it. “It’s not just about the mask, it’s about everything else in and around the use of it that defines whether you have a good mask or not. The patient, the porter, the nurse, the physician, the surgeon, they all have a different pathway through the hospital – the things they touch, they people they get close to. Only with that holistic understanding of exactly how people and things move around can you really start to put in place a safe environment for patients and providers.”

Occupational hygiene – the discipline of managing hazards at work – also views PPE as the last line of defence in a much wider system. Peter Aspinall, principal occupational hygienist with WSP in Brisbane, is a former nurse himself, though these days his work focuses mainly on industrial workplaces. “We talk about a hierarchy of controls,” he explains. “We start by trying to eliminate the hazard, then we look at mitigation through engineering design. If you walk into a mine today, it’s totally different compared to 50 years ago. That’s what’s going to have to happen in hospitals. We need better designed workflows through hospitals and better ventilation, so that these areas can be as safe as possible. The piecemeal fixes that we’ve used for COVID like outdoor screening clinics are not sustainable.”

Starting from the top of the occupational hygiene hierarchy, an important way to reduce the risk is to manage the flow of potentially infected people through a hospital building or campus. Bracing themselves for a surge in COVID patients, healthcare systems had to respond quickly with temporary fixes, such as triage tents in parking areas. For the longer term, a pandemic operations plan will be essential for both existing and new facilities. “Our clients are starting to look at how they can get a patient who presents at an emergency department to an exam room and to a patient bed with the lowest amount of risk,” says Kevin Chow, senior associate and healthcare specialist at WSP, based in Dallas. He is involved in the design of a hospital tower on a healthcare campus in Fort Worth, Texas, where the emergency department (ED) is in a separate building. “If the ED sees a surge, this tower might become a place to put infectious patients. The tower has a pre-admit testing space on the first floor, so we’re looking at having a separate entrance and parking area, to bring in infected patients in a single flow, get their vital signs and take them up to a dedicated floor. Normally we would assume that everyone would go to the ED, but we are looking at different options for this level of surge that don’t involve tenting.”

What about the working environment itself? Hospitals are already designed and operated to reduce infection from contaminated surfaces. Cleaning is frequent, nooks and crevices are designed out, and surfaces are wipeable, with antimicrobial materials and coatings. There may be opportunities to install additional touch-free controls in bathrooms and on doors, and to increase the number of hand hygiene stations and sanitiser points. Robot cleaners can reduce the risks for human teams by disinfecting rooms with UV light before they go in.

Aside from people, airflow is the other key transmission route for disease. Ventilation and air-conditioning plays a vitally important role in controlling the spread of infection in a hospital, not only by purging spaces of airborne pathogens, but by creating negative or positive pressure relationships that either prevent air from escaping or entering a space. Isolation rooms for infected patients are negatively pressurized so that nothing can escape; operating theatres and protective spaces for the immunocompromised are positive so that nothing can enter.

Research is ongoing into the routes by which the SARS-CoV-2 virus that causes COVID-19 is transmitted. The World Health Organization’s latest guidance, published in July 2020, says that it spreads from person to person through infected secretions such as saliva, or via respiratory droplets that are expelled when an infected person coughs, sneezes, speaks or sings. These may be ingested by a person in close contact (within 1m), or they may fall onto nearby surfaces, where the virus can survive for a period of time from a few hours to several days. Airborne transmission of SARS-CoV-2 can also take place during medical procedures that generate aerosols – smaller particles that may remain suspended in the air over longer distances and time periods. Scientists continue to debate and investigate whether airborne transmission may occur in the absence of these procedures, particularly in indoor settings with poor ventilation.

The coronavirus that caused the SARS epidemic in 2002-04 was fully airborne, and this proved a transformative experience for hospital design in Asia. COVID-19 is likely to do the same for the rest of the world. “In Singapore, hospital design has evolved in quite a significant way since the SARS outbreak,” says WSP principal Lionel Neo, a specialist in engineering healthcare buildings. In the aftermath of that epidemic, Singapore’s government hospitals adopted a range of measures to improve indoor air quality, including purging systems, higher air-change rates, higher levels of filtration, and UV light and titanium coatings on cooling coils in air-handling units to kill bacteria and viruses, says Neo. “When COVID-19 hit, the systems were already in place, and hospitals were mostly considered pretty well-equipped to tackle it.”

These measures are not in place all the time – in Singapore’s tropical, humid climate, the cost and energy required to constantly refresh all the air would be enormous. Instead, systems have dual ventilation modes, so that in the case of a pandemic – or a severe air pollution event, as caused by forest fires in neighbouring Indonesia in 2019 – they can be switched to fully exhausted, isolation, or mechanical ventilation and spot cooling mode.

To achieve this, air handling is strictly zoned in new hospital designs. “That starts from floor-by-floor planning, then zone-by-zone, and then department-by-department,” says Neo. “An air-handling unit is not shared by more than one department, so that the air-handling operation can be contained within that department itself.” Ventilation systems are designed to mirror the workflow of each department – so in a sterile services unit where contaminated equipment is returned and cleaned, air flows from sterile to clean to dirty areas before being exhausted out.

Singapore’s hospitals are already fitted with prefilters with a MERV rating of at least 7, and a secondary filter of at least 14, but there are also empty slots so that HEPA filters (MERV 17 or higher) can be added during a pandemic or air pollution event, and fans are sized to handle the additional resistance that this creates. “In terms of the whole hospital project, the cost is marginal – a fraction of the total project cost,” says Neo. Increasing floor-to-floor heights has a greater knock-on effect: in more recent designs, a standard 4.3m has been raised to 5m or ideally 6m. “The extra air changes, purging and dilution that’s required pushes up the need for ceiling space, so floor-to-floor heights inevitably have to increase as well to give us a bit of headroom, especially in light of COVID. Provision for extra and well-placed mechanical ventilation risers should also be considered during the planning. When it comes to fitting out existing buildings with smaller heights, it can be quite a challenge.”

Another feature of Asian hospitals is a much greater number of isolation rooms for patients with airborne diseases, to prevent infection spreading to the rest of the hospital. These are essential for aerosol-generating procedures such as intubating critically ill patients before placing them on a ventilator. Elsewhere in the world, there are typically very few, and they are often scattered throughout different acuities. “Isolation rooms became extremely important during COVID, but we just didn’t have enough because we hardly ever needed to use them – a typical 100-bed hospital might have four,” says Gary Hamilton, an HVAC specialist and healthcare practice leader at WSP, based in Washington DC.

True isolation rooms are completely sealed and gasketed, with hard, wipeable ceilings, and equipped with HEPA filtration, two fans in case of failure and emergency power, as well as a pressure display and alarm so that staff know it’s safe to enter. During COVID, hospitals were forced to improvise negative pressure in normal rooms by installing fans extracting to the outside, and disconnecting return vents or installing higher-quality HEPA filtration to prevent the infection spreading through the hospital ductwork. “There’s an extreme amount of risk associated with using regular patient rooms without any treatment or diversion of the air going back to an air-handling unit,” explains Chow. “If the duct systems are interconnected with spaces not utilized for pandemic operations, you could be spreading contaminants from a COVID area to other parts of the hospital.”

Healthcare systems are now reviewing options for increasing isolation capacity. One option is to install entire floors of these rooms in major hospitals, so that staff can be properly trained in how to use them before an event occurs, and then infectious patients would be centralized in that location. Another is to design normal patient rooms so that they can be switched to negative pressure and fully exhausted in the event of a pandemic. This is common practice in Asia – at Kwong Wah Hospital in Hong Kong, WSP engineered a 176-bed isolation facility, and 162 further beds that are convertible to isolation mode if needed, out of a total of 1,140.

But rooms with switchable pressure relationships are not necessarily permitted under current building codes elsewhere, for example in some US states. The objection is not the switch to pandemic mode; it is what happens when you switch them back. With an airborne infection isolation (AII) room, all of the air is always fully exhausted all of the time, so it just needs to be disinfected between patients. A switchable room will be fully exhausted during a pandemic event, but the air will have to travel through a section of ductwork before it reaches the exhaust fan. When normal operations resume and air is again returned through that ductwork, there is a risk that some pathogens will remain. “When HVAC systems are utilized in areas with infectious disease patients, there is a risk that contaminants have settled in the duct,” says Chow. “To mitigate the risk, you would want to make sure that you’ve cleaned that ductwork all the way through.” But cleaning ductwork isn’t a regular part of hospital maintenance: “There are ways to do it, but it’s not something that a typical healthcare facility has ever had to deal with. Code requires that hospitals use filtration to make sure that air going down the supply ductwork is clean, but the particles from this virus are not large enough to be caught by the normal filtration required for patient rooms.”

There remains the question of whether HEPA – high-efficiency particulate air – filtration is sufficient, or whether it is necessary to go to the next level: ultra-low particulate air (ULPA) filtration, which catches 99.999% of particles as small as 0.1 μm.

During COVID, many hospitals have also installed HEPA filtration on exhaust systems to properly treat air from isolation rooms before it is ejected from the building. “There is a concern that contaminated air is discharged where it could be breathed in, or entrained in the outside air of an air-handling system serving an adjacent building,” explains Chow. Going further, high-velocity plume fans are installed for laboratories or pharmacies preparing chemotherapy drugs: “Fan discharge velocity is used to create a plume high enough for dilution to mitigate a potential threat. High-velocity plume fans in conjunction with high-efficiency filtration would be considered for a true airborne pandemic.”

Whether COVID-19 is proven to be fully airborne or not, it should serve as a warning, says Hamilton, and a spur to more forward-thinking, resilient planning. “For the future, all hospital systems will absolutely have to be designed to meet these extra requirements. We need to create a healthcare system that can help us to cope with any kind of future pandemic – we can’t afford the risk of having a system that is unable to handle something like this.”

Of course, hospitals must not only be safe – they must also be perceived to be safe or they cannot perform their essential role. There is worrying evidence that people who have needed medical assistance during COVID-19 have been too frightened to do so for fear of catching the virus. So can we reassure them? We’ll consider this in the next part of the series.