It’s early January, that time of the year when many humans make an annual migration to the gym in a desperate bid to undo last month’s overindulgences. If you’re looking for last-minute inspiration to get back into working out, however, we suggest you avoid reading this new portrait of gym air quality.
A new study, published in the journal Indoor Air, has shown how the air in a bustling gym contains a cocktail of chemicals from human breath, sweat, and cleaning products. One sweating, huffing, exercising person emits as many chemicals from their body as five people standing still, the study found. Strangest of all, the researchers noted how amino acids from sweat or acetone from human breath can chemically combine with disinfectants around the gym equipment to form new airborne chemicals – the impacts of which we don't yet know.
Scientists at the University of Colorado Boulder created a weight room on their campus and fitted it with air-sampling gadgets with the aim of monitoring airborne chemicals in real-time before, during, and after workouts.
Along with pumping out carbon dioxide during a workout, humans also expel a concoction of volatile organic compounds (VOC), organic chemicals that can easily evaporate into the air, through their breath and sweat. The types of VOCs a person expels can depend on their diet, whether they smoke, and their wider health. Indeed, the presence of particular VOCs can even be used to identify whether a person is suffering from certain diseases.
Unsurprisingly, more VOCs are also expelled via the breath and sweat during vigorous exercise. The researchers note that the athletes' bodies produced three to five times more emissions while working out, compared to when they were at rest.
But it isn’t just humans that produce VOCs, they are also emitted by a wide array of products, from paints and pesticides to cleaning products and deodorants.
The new study found that the gym air became filled with relatively high concentrations of N‐chloraldimines after the equipment has been wiped down with bleach-based cleaning sprays. They believe this chemical was created by reactions of free amino acids released from sweating bodies with disinfection agents on gym surfaces. Similar reactions involving products of ammonia with bleach have been found to be harmful to human health, although scientists aren’t exactly sure what effect this change in air quality might have on human health.
“Since people spend about 90 percent of our time indoors, it's critical we understand how chemicals behave in the spaces we occupy," Joost de Gouw, professor of chemistry at CU Boulder, said in a statement.
There is also some good news. Although the study was carried out before the COVID-19 pandemic, the researchers say that their study on air quality in gyms does suggest this environment is relatively safe, provided people maintain some social distancing and the space is well-ventilated.