Not changing your clothes can alter your room’s ozone chemistry

Our daily habits, like how often we shower or change our clothes, depend on our environs and sometimes also on our energy levels. But obviously how dirty we are also affects our immediate environment. Atoms and molecules in the air can react with compounds on our skin and clothes to form airborne chemicals.

In a new study, researchers from China, Denmark, and the U.S. tested how our habits affect which chemicals are formed. Their findings are (un)pleasantly surprising. They found that not bathing for three days made almost no difference because glands quickly replace the oils on the skin that have been washed off. However, wearing the same unwashed clothes for three days boosted ozone-generated chemicals in the air by about 25%.

The researchers built a steel chamber about the size of a telephone booth and asked three healthy men in their 20s to sit inside for two to three hours at a time. A snorkel-like mask sent each volunteer’s breath outside the chamber, where instruments received the emissions from their skin and clothes. Fresh air flowed through the chamber about twice every hour, and the researchers could either keep ozone levels very low (under 2 parts per billion, ppb) or add a gentle 10 ppb breeze of ozone similar to that during a clean, sunny day outdoors.

In separate test runs, the team varied one of temperature, relative humidity, personal hygiene or clothing coverage while keeping the other settings constant.

Outside, they continuously analysed the air from the chamber with a sensitive mass spectrometer that tracked 11 marker chemicals, including acetone, 6-methyl-5-hepten-2-one (6-MHO), geranyl acetone, and several aldehydes. These compounds are well-known byproducts of the reaction of ozone with skin oil.

This way, they found that temperature and humidity hardly mattered. Between 22° C and 28° C the total ozone-driven emissions stagnated at around 4 micromoles per square metre per hour. Changing the relative humidity from 40% to 70% also left emission rates unchanged.

However, while not bathing made little difference either, sticking to the same clothes for three days increased the production of 6-MHO and geranyl acetone, derived from squalene on the skin, by up to 77%. Clothes-only tests confirmed that fabric coated with old skin oil becomes its own chemical plant.

The study was published in ACS Environmental Au on June 29.