MIT App Helps Businesses Quantify COVID-19 Risk, Safety

MIT App Helps Businesses Quantify COVID-19 Risk, Safety
By Alexandra Black Larcom

By Alexandra Black Larcom


An online app can help shed light on what you can do in your health club facility to decrease the risk of COVID-19 spread by taking into account ceiling height, MERV filters, human behavior, and other factors that affect indoor spaces.

One of the biggest concerns surrounding health club operations during COVID-19 has been the potential for airborne transmission, and the increased risk associated with indoor spaces. However, scientists increasingly recognize that not all indoor spaces are created equal. A well-ventilated health club implementing social distancing, cleaning, and mask wearing does not carry the same level of risk as a less well-ventilated restaurant in which patrons are sharing a table with members outside their household while not wearing masks.


In order to help us better understand and quantify risks associated with indoor spaces, two scientists at the Massachusetts Institute of Technology (MIT), Martin Z. Bazant and John W. M. Bush created a model for COVID-19 transmission in a well-mixed room factoring in a number of variables. The model underpins the open access app, and is built based on existing models of airborne disease transmission. Variables in the model include:


  • Room dimensions
  • Ventilation parameters, e.g. MERV rating and air changes
  • Breathing rate
  • Respiratory activity, e.g. exercising, talking, singing
  • Mask type and mask compliance


The app calculates the number of people who can be in a given space for a certain amount of time before theoretically being exposed to COVID-19. The calculations and evidence supporting the app is outlined in a paper, Beyond Six Feet: A Guideline to Limit Indoor Airborne Transmission of COVID-19, currently undergoing peer review.


Understanding Risk and Safety Parameters—But No Guarantees


This app can help club operators understand the different modifiable factors in their facility that can impact COVID-19 safety, and shed light on the impact these adjustments can have. For example, if you cannot upgrade your MERV filter or your building has a low ceiling height, this app can help you figure out other factors you can adjust to make your space as safe as possible. Every building and facility will have different inherent strengths and different capabilities when it comes to upgrading HVAC or increasing outdoor air. For example, a small studio with low ceiling height may be able to improve safety by increasing mask use. A gym with high ceilings and a garage door may not be able to update their MERV filter, but they can open the doors and windows to increase outdoor air circulation.


This app does not, however, provide any guarantees or complete assurances with regards to safety. If the output shows that 80 people can be in your facility for 75 minutes before a theoretical exposure occurs, this does not guarantee that having 80 people in your club for 75 minutes will never result in a COVID-19 exposure. For one, the app assumes only one person in a given room is infected. If more than one person is infected, the dynamics would change in a way the app does not capture.


Keep in mind the app is based on modeling and assumptions and is not perfect. If it provides a result that does not make sense—for example, a number of people that can occupy the space in excess of your fire code—check to make sure all the inputs are accurate. Square footage should be limited to the specific workout space and not include back offices, locker rooms, etc. Group exercise rooms should be calculated separately from the main fitness floor.


Using the App


The app is straightforward and comes with a set of instructions. It is worth mentioning that because the app assumes one person is a transmitter, when you select for respiratory activity—heavy breathing or talking loudly—you must select this option if anyone may be doing it. For most fitness facilities, that likely means “talking softly” should be selected to account for member and staff conversations. If you are assessing a group exercise class, select “talking” or “talking loudly” depending on whether the instructor will have a microphone. Even if the instructor is the only one talking, the safest assumption is that they might be the infected person.


Clubs can use this app to gain a better understanding of the modifiable risk factors associated with its space, and to estimate how adjusting certain parameters impacts capacity and relative safety. Complete safety is something we can never guarantee—in the midst of a pandemic, risk can never be zero. But we do have a number of factors already in our favor—building dimensions, the ability to wear masks during exercise, enhanced ventilation and filtration—that increase the relative safety of fitness centers compared to other indoor venues.


Clubs can also use the output from the app to help educate policymakers, members, and other stakeholders about the safety protocols the club is putting in place and their impact on relative risk.


‘Heavy Breathing’ May Not Be As High Risk as Once Assumed


Aside from the app, this paper provides another interesting finding: that heavy breathing, often used to support the assumption that health clubs are inherently less safe than other places, may not be as high risk. Two graphs included in the paper show the volume of aerosol particles of varying sizes in the air with rest, heavy breathing, and talking and singing at various levels. At the average particle size of 2.6 micometers, the difference in concentration between nose breathing (at rest) and mouth breathing (more typical with exertion) is minimal.

Courtesy: Medrxiv

Throughout this pandemic, health clubs have led the way on implementing enhanced safety protocols. Clubs provide a relatively safe, controlled environment for people to remain physically active and have reprieve from isolation. In light of new evidence that exercise capacity may be linked to lower risk of COVID-19 hospitalization, a lower risk place to improve health and fitness is vital.

Alexandra Black Larcom, MPH, RD, LDN, is the Senior Manager of Health Promotion & Health Policy for IHRSA. She spends her days working on resources and projects that help IHRSA clubs offer effective health programs in their communities, and convincing lawmakers that policies promoting exercise are an excellent idea. Outside the office you’ll most likely find Alex at the gym, running on the Charles River, or, in the fall, by a TV cheering on the Florida Gators.




The International Health, Racquet & Sportsclub Association (IHRSA) is a global community of health and fitness professionals committed to building their businesses and improving their communities’ health and well-being. The mission of IHRSA is to grow, protect, and promote the health and fitness industry, and to provide its members with the benefits that will help them be more successful. IHRSA and its members (health clubs and fitness facilities, gyms, spas, sports clubs, and industry suppliers) are dedicated to make the world healthier through regular exercise. For more information visit

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