Safe indoor work-outs during the COVID-19 pandemic

Abstract

Many people go to the gym to work-out or take part in classes to remain in good physical health. During the COVID-19 pandemic, gyms in most countries across the world were obliged to close to prevent the virus from spreading during indoor work-outs. Indeed, the risk of aerosol virus transmission during high intensity exercise is significantly increased due to the increased aerosol production of a potentially infected person and the increased breathing volume of susceptible individuals. However, doing physical workouts is of great importance to stay healthy and enhance the immune system, especially during the pandemic, since it is known that overweight people and people with underlying diseases are at increased risk. Therefore, the objective of this project was to design a ventilation and air cleaning system that significantly reduces the risk of aerosol virus transmission in indoor sport environments. The project aims to contribute to establishing requirements for indoor sport facilities in terms of ventilation and air cleaning such that, during a next lockdown, gyms that fulfil these requirements can remain open. To achieve this objective, a literature survey was conducted to map the current knowledge on the aerosol transmission of COVID-19 and the characteristics of different types of exercise. Based on that, requirements were set for different intensity group classes to maintain the CO₂ concentration below 1200 ppm and the theoretical Wells Riley-infection risk below 5%. In addition, the importance of ventilation efficiency to dilute released contaminated aerosols was well understood in order to apply the Wells Riley-model. A lab- and field study were conducted to test if the model assumptions were met. Also, the possibility to measure aerosols in the field was investigated. Based on these outcomes, a prototype consisting of a ventilation system, air cleaning system and cooling system combined with a smart control algorithm, was designed and installed in a room for group classes. The performance of the systems was tested during exercise classes of yoga, zumba and indoor cycling (spinning).