The scientists expected that as the intensity increased, the exercisers’ aerosol production would increase. As we work hard, we all take deep and fast breaths. But the extent of the increase “surprised us,” said Henning Wackerhej, professor of exercise biology at the Technical University of Munich and a senior author of the new study.
The increase in aerosol emissions began modestly as riders warmed up and began pedaling harder. But as they approached the threshold at which their exercise became more strenuous—when a jog becomes a run or a spin turns into a class interval—the increase in emissions becomes exponential. Riders began to expel about 10 times more air per minute than at rest, while the number of particles per minute increased by more than 100 times as riders approached exhaustion (with considerable variation from person to person). .
In a room full of spin-bike riders, treadmill runners or boot campers, “the aerosol particle concentration will increase greatly,” said Benedict Mush, a graduate student at the Institute of Fluid Mechanics and Aerodynamics at the University of the German Armed Forces. in Munich and co-author of the study. The more particles there are, the higher the chance of a COVID-19 infection if an exerciser is infected.
“The study provides mechanistic data to support the notion that exercising indoors is a high-risk activity when it comes to transmission of COVID-19,” said Linsey Marr, professor of civil and environmental engineering at Virginia Tech. is”. and experts on airborne transmission of the virus.
But these risks can be reduced. “Good ventilation and air exchange is a great way to reduce transmission risk,” said Chris Kappa, a professor of civil and environmental engineering at the University of California, Davis, and an expert in airflow dynamics.
“Open windows, especially those with fans, can often be effective as an active ventilation system,” he said. If your gym windows are closed, ask the manager to widen them and crank the wings. If the weather is oppressive and air conditioning is necessary, make sure your gym’s units draw air from outside, so the fresh supply replaces the air laden with aerosol emissions from you and your classmates.
You can also suggest that gyms install in-room air filters in each workout area, Dr. Kappa said. “These can be really effective in reducing transmission risk by removing the virus from the air.” They can be bought commercially or even made at home, he said.