Clearing the Air – Delos’ classroom air-quality study, and what hoteliers can learn from it

The hotel industry has always been aware of indoor air quality, but no more so than during the COVID-19 pandemic, where concerns of the transmission of the virus plagued every hotelier, from the operator of big-box hotels to the mom-and-pop, single-property hotel owner.

Indoor air quality has also become a major concern of guests. A study earlier this year of 1,000 U.S. consumers by Carbon Lighthouse found that 91% of respondents understood that indoor air quality is critical in the continued fight against COVID-19, and that 525 said they would pay more to stay at a hotel with better indoor air quality.

The subject has been studied for about five years by Delos, a wellness real estate and technology company guided by the mission to improve the health and well-being of people around the world by improving the indoor environments where they live, work, sleep and play.

“We spend [more than]90% of our time in the indoor environment—our homes, our schools, our offices, etc.,” said Peter Scialla, president/COO, Delos. “The indoor environment is having a profound impact on our health and well-being, and there are things we can do to influence the outcomes. Thankfully, with the help of technology, we’ve made a lot of progress over the last decade, pioneering the WELL Building movement and then specifically diving into categorical expertise.”

The executive pointed out that air quality has implications for many different health outcomes, including susceptibility to long-term disease and acquired infections.

“More recently, the real area of public concern from the pandemic started with surface hygiene, but moved very quickly into a recognition that this is an airborne concern and that pathogen transmission is something that happens through particles in the air,” Scialla said. “Therefore, we increased our resources, studies and focus on air as a category, with a strong baseline of support going into the pandemic and now, of course, acceleration through the pandemic because of the world’s focus on indoor air quality. And we’ve continued to translate that into calls to action on things that can be done to improve the indoor environment, getting very specific on actual mechanisms of action and approaches that we feel are right for adoption and that can drive meaningful change.”

In order to provide the best solutions to the indoor air quality issue, we must separate fact from fiction, according to Dr. Zachary Pope, research scientist, Well Living Lab.

“The ability to do that with science is really instrumental to what we try to do across the Delos organization, and definitely here at the Well Living Lab, being part of Delos,” he said. “To the point Peter mentioned about giving people actionable things they can do, I think that is ultimately when we start thinking about indoor air quality, especially right now given the pandemic and how that’s put air quality front and center on everybody’s mind. Being able to do that and having the resources to do that is really where I think we’ve invested a lot of attention and energy.”

Details of the study

Because of the pandemic, some schools were closed for more than a year and, consequently, students took to their computers for virtual classes. When it was deemed safe to return, schools reopened, but concerns remain about viral transmission through the air, especially in a classroom with a large number of students.

The Well Living Lab, in collaboration with the Mayo Clinic and the University of Minnesota, performed a study to find out if adding portable air purification units would help to keep the air clean from viruses and other harmful airborne particles. Within the Well Living Lab’s research space, a 1300-sq.-ft. office module was converted into a 900-sq.-ft. classroom, complete with strategically positioned equipment, such as desks, whiteboards and iPads, and the air-purification units.

“First, we concentrated on what’s in the air,” said Pope, who led the project along with Barbara Spurrier, executive director, Well Living Lab. “We used optical particle sizers that are able to tell you per cubic centimeter how many particles are floating around. It does that through its own internal mechanism, and we actually used two of those devices during each of the trials. Additionally, to assess the mass of aerosols in the air, we used impingers—little glass pieces of equipment that you hook onto vacuum pumps, and they’re going to suck in any aerosol present within roughly a 3-to-6-ft. radius.”

To stimulate the act of breathing of teachers and students, a breathing simulator was connected to an anatomically correct respiratory manikin, which mimicked inhalation and exhalation and exhaled air particles of 1-to-3 micrometers in size—the particle size most implicated in airborne infectious disease transmission. The particles were tagged with a fluorescent dye so that they could be measured, and Intellipure Compact Air Purification System units were used.

On why the specific unit was chosen, Scialla said, “The goal was to be a source of truth, eliminating variables and any bias towards one product or another. We surveyed more than 100 different air-purification devices. There are so many variables that can change the outcome between the filter’s efficiency and how that’s rated versus the real-world outcome of how efficient air is getting filtered when the device is put in a room and turned on. So, total device efficiency was a metric that we used as a real source of truth as it relates to the best recommendation in this regard. In all of our testing and examination of specifications and third-party lab results, this Intellipure unit came out on top for total device efficiency.”

Using the particle sizer and impinger, the scientists were able to study the amounts of particles in the air at different points in the room. “That gave us the ability as we moved those pieces of equipment around to then draw out those contour plots that really showed how effective portable air filtration is in the vicinity it affects when you’re running that unit or those units in a space as a supplement to that space’s HVAC system,” said Pope.

The study also focused on how the particles accumulate onto different surfaces because other viruses and pathogens can transmit on surfaces.

“We used plastic wrap and Scotch Tape in different locations,” said Pope. “You have what’s in the air with that optical particle sizer and the impinger, and then you have the plastic wrap and the Scotch Tape that really lets you look at surface accumulation. With those plastic wrap and pieces of Scotch Tape, we’re able to go back and measure the mass of the fluorescent dye that we had within the aerosolized particles.”

He added, “We’re then able to make a statement of, ‘OK, here’s what we saw in the air, here’s also what we’re seeing on different surfaces.’ So, really attacking the transmission of aerosols at two different levels because even though the aerosol transmission route is likely the predominant route of transmission for not just SARS-CoV-2—the virus that causes COVID-19—but other viruses, it’s still important to take a look at also what’s going on when you are adding something to the space to clean air.”

The study found that, with three air-purification units in the room, there was a decrease in the number of particles in the air of more than five times.

“That’s pretty astounding, and it was also nice to see how global it was,” said Pope. “You weren’t just seeing it in one area of the room within a very small space around the unit itself; you were

seeing it really throughout the room.”

The study also found that, with the Inellipures working, 33% less accumulation of particles were seen on surfaces throughout the room.

“That’s really important when you start thinking about high-touch surfaces and any possible fomite transmission that might be happening,” Pope noted. “If you’re thinking about classrooms, it’s really hard to get—no matter what age they are—children and adolescents to stop touching their face, their nose and all these mucous membranes where really any virus can gain entry to the body.”

What hoteliers can learn

While the study was done in a classroom setting, similar conclusions can be made for a hotel guestroom or public space.

“In many ways, classrooms are different environments from hotels, but in many ways they’re identical,” said Scialla. “[They’re both]  indoor environments surrounded by four walls and a roof, and perhaps the ability to increase ventilation with windows. But, the science tells us that airborne transmission of viral particles or particles that attach to bigger particles in the air don’t discriminate whether they’re in a classroom or in a hotel. The facts are facts, the science is science. So, when you’ve got any space, whether it’s a classroom or a 350-sq.-ft. hotel guestroom, a 1,000-sq.-ft. meeting space or a hotel lobby, it applies. Any indoor environment is subject to the same conditions and, therefore, subject to the same risk of particle or viral transmission.”

Pope firmly believes that the results are transferable to hotels, and added that for hoteliers to find the right air purification system for their needs, there are some really simple things to look for.

“Look at [the unit’s]square footage coverage, which almost every manufacturer is going to post on its website or in user manuals,” he said. “Also, find the clean air delivery rate, and those work in tandem. The higher the clean air delivery rate, typically you have a greater square footage coverage. For instance, in our classroom study, we had to use three purification units because we needed that to adequately cover the space. They were spread equal distance throughout the room, so that the room was covered.”

Some companies offer multiple options depending on the size of the space. “If you’re looking at Intellipure, there’s three different options that might be more or less appropriate for different environments,” said Pope. “Intellipure Compact may be great for a hotel room, but for the lobby there’s a commercial unit that would be appropriate for that space.”

Multiple units in one space may be the answer, Scialla pointed out. “If there’s a big meeting space that requires three or four units as opposed to one, that provides actually a benefit with it. You have increasing points of filtration and that activity is important, especially when you can [place the units]as close as possible to where people are convening.”

Pressure drop is another concern that hoteliers should be aware of. “The thing that is unique about the Compact unit is the technology placed within it minimizes pressure drop,” said Pope. “What pressure drop ultimately does is increase energy expenditure. If you have more pressure drop, the fan has to work harder, you spend more energy. That might not be a good thing, especially in some older spaces, which may not have a power grid breaker box that can really handle that.”

Other ways to provide clean air

There are, of course, other things hoteliers can do to provide clean indoor air besides filtration. Ventilation is one if it is feasible, Scialla noted, as well as the types of furniture and mattresses that are used.

“There are mattresses out there that have off-gas chemicals and VOCs—volatile organic compounds—which are extraordinarily unhealthy for the human body, especially when you’re sleeping on it for hours,” he said. “So, I think choice of furniture, choice of materials, choice of wood, choice of paint, choice of mattress [can affect air quality]. Those materials do contribute to poor indoor air quality and contribute largely to why indoor air quality is predominantly so much worse than outdoor quality in almost every case, except for highly polluted cities.”

Pope pointed out that portable air-purification units may ultimately be a better fit because ventilation may be limited or not available at all. “You may not be able to ventilate the space with outdoor air,” he said. “Hotel rooms are the perfect example of that. If you’re able to open a hotel room window, it’s probably that little crack at the bottom or you’re able to bump it out just a tiny bit, but that may not give you everything that you need to really ventilate that space.”

He also suggested looking at the different MERV-rated filters that go into the air-handling unit, adding, “but then you run into pressure drop. It’s a problem in vertical units, but it’s also a problem in those air-handling units, too, because it increases energy expenditure, and that sometimes is not a good thing. Further, with those units that can actually damage the air-handling unit itself because it overworks it.”

His final advice was to open an outdoor air damper on the HVAC units, which pulls in more outdoor air when open, when the weather allows it.

“The problem with that is if you live in Rochester, MN, and it’s minus-20 degrees outside, you can fry your air handling unit,” he noted. “That’s not good either. That’s why, obviously, you want to look into all of these other options if you can, but a scalable option is still that air purification unit.”

Scialla concluded that using portable air purification units will likely be the best option for hotels large or small.

“Outside of checking the scientific boxes and finding the best technology to be that source of truth, we also considered scalability and cost,” he said. “The good news is that the portable wall-mounted approach to [the Intellipure unit]in particular has been deployed on a mass scale—hundreds of thousands of units all over the country, and now internationally as well. And because we’ve captured those efficiencies, being able to provide something that is super scalable and low maintenance and virtually no labor at the price point that the market is receiving the benefit of, it just gives you the final answer: Best-in-class science, best technology, best outcome and the most cost-effective option, as well. That’s tough to argue against”