Air intakes on Boston’s Prudential Center loom over Joseph Allen, who stresses the need to draw more outside air into buildings.
Joseph Allen runs a major public health research project at Harvard University, probing how indoor air quality affects human health and cognition. He consults with companies on ventilation and air filtration, and during the pandemic he became a prominent voice on public health, writing dozens of op-eds criticizing early guidance from health authorities and debunking misconceptions about how the virus spreads. But none of it would have happened if he hadn’t washed out as an FBI recruit.
The son of a New York City homicide detective who opened his own investigative agency, Allen spent his teens and 20s helping with the family business. He did surveillance, undercover work, computer forensics, and skiptrace—tracking down people who left town to avoid alimony. Eventually he took over the agency, leading investigations and supervising eight agents.
“I enjoyed the work and thought it was challenging,” Allen recalls. But part of him always wanted to be a scientist. He majored in environmental science at Boston College, and in his late 20s, still torn, he began to apply to graduate school even as he started the process to become an FBI agent. After 2 years of interviews and testing, the last step was a routine polygraph test. He failed the first round—the trick questions he was asked were so obvious that he could not take them seriously. So FBI flew in one of its toughest examiners from Iraq—a hulking, jackbooted guy who got right in Allen’s face, screaming that he knew he was lying. But Allen kept cool, and after a while, the interrogator stormed out and slammed the door.
“I thought he would come back in the room and say, ‘Congratulations,’ cause I’m thinking I’m crushing it,” Allen recalls. “But they failed me because they said I employed countermeasures.” FBI apparently didn’t want an agent who couldn’t be unnerved by a polygraph test. And that solved Allen’s career dilemma. “I guarantee I’m the only public health student ever to fail an FBI lie detector polygraph in the morning and start graduate school a few hours later,” Allen says. But his investigative instincts never left him.
A tall, athletic-looking man with a bald head and stylish stubble, Allen directs the Healthy Buildings Program at Harvard’s T.H. Chan School of Public Health, where he studies the effects of toxic gases emitted from furniture, carpets, and paints; stale air; and high levels of carbon dioxide. Years of studies by Allen and others have shown poorly circulated air in buildings impairs our ability to think clearly and creatively. Considering that we spend more than 90% of our lifetimes indoors, those findings have implications for personal well-being—and for businesses concerned about their bottom line.
“Joe has always had a unique understanding of this range of domains—from how buildings work, to environmental exposure assessment, to making connections with health outcomes,” says Brent Stephens, chair of the Department of Civil, Architectural, and Environmental Engineering at the Illinois Institute of Technology. “There’s not a tremendous number of people in this world that have worked on that whole spectrum.”
When the COVID-19 pandemic arrived, the previously esoteric field of indoor air quality suddenly became the focus of widespread concern. Like many of his colleagues, Allen jumped into the fray, advising school systems, police departments, entertainment companies, the Boston Symphony, and a host of other entities on how to make their indoor air healthier, during the pandemic and afterward.
“COVID really changed the conversation,” says Matt Murray, vice president of leasing at Boston Properties, the largest publicly traded developer in the United States and one of Allen’s consulting clients. Before the pandemic, the company would have to explain to bored executives why they should pay attention to indoor air. “Now, the CEOs are all saying, ‘What filters do you use? How you process the air you bring into the workspace?’” Murray says. “And we’re ready for those conversations because we’ve been working with Joe.”
After he failed his FBI exam, Allen became a different kind of sleuth. For his doctoral thesis at the Boston University School of Public Health, he investigated toxic flame-retardant chemicals released into the air by furniture, and found they were nearly ubiquitous. (The chemicals were later banned.) After graduation he got a job with a consulting firm, where he investigated problems such as toxic emissions from drywall and outbreaks of Legionnaires’ disease, which is caused by bacteria that grow in plumbing and become aerosolized by ventilation systems, showers, or even flushed toilets. Those investigations introduced him to “sick building syndrome,” a problem first identified in the 1970s in which the occupants experience fatigue, itchy eyes, headaches, and other symptoms. Exactly what causes these ailments isn’t clear, but exposure to contaminated air is a likely culprit. Allen became convinced that the building you work in can have more impact on your health than your doctor.
The idea of a healthy building has been made too complicated.
Joseph Allen and John Macomber, Harvard University
In 2014, Allen accepted a position at Harvard, where he soon turned his attention to how the indoor environment can affect people’s cognitive abilities. Many of us have struggled to pay attention during a long staff meeting in a stuffy conference room. Research by Allen and others suggests that lassitude may not be due solely to boredom, but also to the carbon dioxide (CO2)-rich conference room air.
Ever since the energy shocks of the 1970s, buildings in the United States have been made as airtight and energy-efficient as possible. The result was a buildup of toxic volatile organic compounds (VOCs) and exhaled CO2. “Green building standards” introduced in the late ’90s focused on reducing toxic materials and making buildings healthier as well as more sustainable, but they didn’t prioritize indoor air quality and ultimately did little to improve it.
In a multiyear series of experiments, Allen and his team have investigated the consequences. In the first study, published in 2015, they had 24 white-collar volunteers spend six working days in environmentally controlled office spaces at Syracuse University’s Total Indoor Environmental Quality Laboratory. On various days the experimenters would alter ventilation rates and levels of CO2 and VOCs. Each afternoon the volunteers were tested on their ability to think analytically and react to a crisis. (One test, for example put the volunteer in the role of a small-town mayor trying to react to an emergency.) All tests were double-blind: Neither the volunteers nor the study personnel knew that day’s environmental conditions.
The results were dramatic. When volunteers worked in well-ventilated conditions (which lowered the levels of CO2 and VOCs), they scored 61% higher than when they worked in typical office building conditions. When they worked in the cleanest conditions, with even lower CO2 levels and higher ventilation rates, their scores climbed 101%.
To find out whether the results held up in the real world, Allen and his team recruited 109 volunteers from 10 office buildings across the United States. Six had been renovated to create better heat and humidity control, improve ventilation, and lower the use of toxic materials. Four had not. Allen’s team gave each office worker a Fitbit-like bracelet to record heart rate, skin temperature, sleep patterns, and other physiological signs of well-being. Workers also completed a survey each day about how comfortable they felt and whether they experienced symptoms such as drowsiness or headaches. At the end of the week, they took the cognitive tests. Workers in the buildings with good ventilation and lower levels of indoor pollution scored 26.4% higher than those in the unimproved buildings. They also reported sleeping better and experiencing fewer “sick building” symptoms.
Something in the air
Many sources of indoor air pollution can affect human health and cognition. These include particles and gases emitted by furniture and building materials, as well as carbon dioxide (CO2) exhaled by a building’s occupants. Choosing better materials and improving ventilation, filtration, and air processing can help make buildings healthier.
Fresh air enters building
1 Fresh airOutside air is often the best way to ensure indoor air quality. The recom mended exchange rate of four to six room changes per hour can be achieved by opening windows or tuning the ventilation system.
2 Outdoor pollutantsIn areas with high levels of air pollution, experts recommenda high-qualityfiltration and air treatment system.
3 RecirculationConventional forced-air heating and cooling systems recirculate the same air. Better filters and bringing outside air into theventilation system or openingwindows helps improve air quality.
Outdoor pollutantsenter building
4 Off-gassingRugs, upholstery, paints, and cleaning materials can give off volatile organic compounds(VOCs), which can causeirritation and health problems. Choosing better materials is thebest approach.
5 Exhaled C0
A buildup of CO
of poor ventilation can
cause drowsiness and
impair cognition. Outside
air and a well-tuned
ventilation system can
address that concern.
6 ResuspensionRoutine activities such as walking on rugs and plopping down onchairs can raise levels of dust, which can carry pollutants. Better air filtration and cleaning surfaces with vacuums with built-in filterscan help.
Size mattersOf the many particles found in indoor air, exhaled particles smaller than 5 micrometers (μm) have become a focus during the COVID-19 pandemic because they can linger in the air and transmit disease.
Aerosol particles(<5 μm) Pollen, molds(10–15 μm) Grain of salt(60 μm)
“This is really important, interesting work,” says Elliott Gall, an indoor air scientist at Portland State University. “It’s a great example of the kind of interdisciplinary work [that explores] the complexity of indoor air and how it affects us.”
Over time, Allen came to see businesspeople as natural allies who could act on his public health findings faster than government officials. He teamed up with John Macomber, a Harvard Business School lecturer and former CEO of one of the largest construction companies in New England. Macomber was impressed with Allen’s research suggesting a tiny sacrifice in energy efficiency through improved ventilation could increase a business’s bottom line by as much as 10% by decreasing absenteeism and boosting worker productivity. “I realized we’ve been missing the boat,” Macomber says. “We’re chasing pennies on energy when there’s thousands of dollars in productivity issues.”
Allen and Macomber consulted with companies and spoke at corporate conferences, making the economic case for improving ventilation and filtration as well as adjusting lighting, temperature, and humidity. “The idea of a healthy building has been made too complicated,” they wrote in a book they co-authored, Healthy Buildings: How Indoor Spaces Drive Performance and Productivity. “There are just a handful of things we need to do to make a building healthier.”
Allen’s group continued to investigate how the indoor environment affects our mental state. They found that airline pilots exposed to CO2 levels common in cockpits did worse on Federal Aviation Administration–mandated emergency response tests than when they breathed better air. They showed that during a heat wave, students who lived in non–air-conditioned dorms had slower reaction times and poorer problem-solving skills than those with air conditioning. They showed that bringing plants and views of nature into the workplace can lower office workers’ heart rate, blood pressure, and other physiological indicators of stress.
In 2019, Allen’s team embarked on an ambitious international project to examine the long-term impacts of indoor air quality by tracking the physical and cognitive health of more than 300 office workers in 43 buildings in six countries over the course of 1 year. They mailed each worker a wristband to monitor their physiology and a small sensor to continuously measure levels of fine particulates and CO2 in their workspace. At predetermined times and levels of CO2 and particulates, the program pinged each worker’s smartphone with a quiz to test reaction time and cognitive function. The studies showed that in offices across the world, poor ventilation, CO2, and particulates (which carry VOCs) conspire to significantly impair cognitive function.
When the first reports of the new coronavirus emerged from Wuhan, China, in January 2020, Allen realized his years researching air quality and disease transmission in indoor environments had new relevance. “Even though the virus was novel, there are elements in all this that feel quite familiar,” he says. “It doesn’t matter if it’s a radiological hazard, biological hazard, or chemical hazard. We know how to assess the risk and put in appropriate controls.”
Early in the pandemic, experts at the World Health Organization (WHO) and the U.S. Centers for Disease Control and Prevention (CDC) latched onto the idea that the virus was spread by large, exhaled droplets that float for a short time and then settle on surfaces. But scientists specializing in aerosols knew airborne viruses are more likely to ride on tinier particles exhaled when people breathe, sneeze, cough, or talk. Smaller than 5 microns, these particles can travel across a room and linger in indoor air for hours.
Aerosol experts such as Lidia Morawska of Australia’s Queensland University of Technology, Gardens Point; Donald Milton of the University of Maryland, College Park; and Linsey Marr of Virginia Polytechnic Institute and State University argued that the focus on larger droplets had led to wrong-headed guidance about washing packages with bleach, staying 2 meters apart—even outdoors—and other forms of what some researchers called “hygiene theater.” They urged policies that emphasized indoor mask wearing and less draconian regulations for people outdoors, where the virus would quickly disperse.
Allen signed on to that fight, collaborating with aerosol experts and public health researchers on scientific papers and bringing their case to the public. “He’s a really good public communicator,” says Marr, who credits Allen with helping her work get the attention it deserves.
“One of our biggest frustrations over the past year is that we knew enough to act early on,” Allen says. “Even by late January 2020 we knew that airborne transmission of aerosols was not only likely, but probable.” Waiting for proof made no sense. “This was a pandemic, an all-in moment, so why wouldn’t we have immediately deployed every strategy that could have helped?” Those strategies, Allen knew from his research, include bringing more outside air into chronically underventilated buildings and using higher efficiency filters in ventilation units.
One of our biggest frustrations over the past year is that we knew enough to act early on.
Joseph Allen, Harvard University
He started waking up at 4 a.m. to write opinion pieces. His first two, in the Financial Times and The New York Times, argued that buildings, if properly ventilated, could be formidable weapons in the fight against the virus. He and his team had measured air flow in schoolrooms under various conditions, and Allen explained that schools could easily be made safe by opening windows and buying the kind of high-efficiency particulate air purifiers sold at local home stores.
So much of his writing involved correcting misimpressions that he felt he was playing editorial whack-a-mole. No, he argued, you do not have to wipe your groceries with bleach. No, you do not have to avoid exercising outside. No, schools do not need to install costly air-purifying systems.
In July 2020, Morawska and Milton wrote an open letter to WHO—a full-throated appeal to recognize the importance of aerosol transmission. Allen was among 237 other scientists in 32 countries who signed on to the letter, which urged greater emphasis on indoor air quality. But WHO continued to downplay the importance of aerosol transmission. “I think some of the reluctance was that if [health authorities] say a disease is airborne, we’d have to provide N95 masks for every health worker and have negative pressure rooms in every hospital, which wasn’t possible,” Marr says.
Later that month, Allen and his Harvard colleague Parham Azimi published a study in the Proceedings of the National Academy of Sciences that used computer modeling to reconstruct the spread of the COVID-19 outbreak on the Diamond Princess cruise ship. By mapping the ship’s ventilation system and the locations of people who came down with the disease, they showed that only aerosols, not larger droplets, could have traveled the necessary distances through the ducts. Similar findings emerged from studies by Marr, Morawska, and others.
Finally, in early May, after a series of persuasive papers in major journals, WHO and CDC acknowledged that the virus was transmitted primarily by fine aerosols. (Even then, the agencies issued no major announcements but simply changed the wording on their websites.) Since then, CDC has gone further, issuing recommendations for reopening schools that stress the importance of good ventilation in addition to vaccinations.
Meanwhile, Allen and his colleagues at the Harvard Healthy Buildings Program created a website with a comprehensive guide to maintaining proper ventilation in schools, homes, and businesses. The website advises building managers to bring in as much outside air as possible—a room air exchange rate of four to six times per hour, more than double the rate in a typical office or school building. In buildings that recirculate interior air, managers should upgrade to hospital-grade MERV 13 filters, which remove up to 90% of particles 2.5 microns or smaller, rather than the typical MERV 8, which can remove as little as 20%.
The new focus on indoor air quality could help hasten the end of the current pandemic and perhaps even help forestall the next one. It may bring broader changes as well. Businesspeople are recognizing the value of improving indoor air to create better working conditions and add value to their properties. “What we’re seeing with some parts of the market—notably the higher end, real estate investment trusts, owners of multiple office buildings or apartments—is they’re thinking really hard about competing” in the post pandemic market, Macomber says. “And one way to compete is to have healthier buildings.”
Allen predicts that the new availability of cheap personal air quality monitors will quicken that competition and heighten people’s awareness of the indoor environment. Previously, the only way to assess indoor air quality was to hire an expensive consultant. Now, with monitors available online for less than a couple of hundred dollars, any office worker or hotel guest can quickly monitor CO2; some devices even detect VOCs. If consumers post results on websites like Yelp, businesses would be forced to pay attention. (Indeed, some building owners already boast about air quality in advertisements.)
“I think there’s going to be a fundamental rebalancing in terms of how we think about indoor spaces,” Allen says. “I think that people won’t tolerate sick buildings, where you feel tired, your eyes itch, you have a headache, or you’re stuffed into a closetlike office with no windows.” It’s one lasting positive from the pandemic. “That era is over,” Allen says. “Rightly so, and good riddance.”