When our skin comes into contact with ozone, nanoparticles are created that are spread further through the air and may even develop into a serious health risk.

Researchers write that in the magazine Environmental Science & Technology. They are based on experiments in which volunteers were placed in a room and then exposed to ozone (see box).

You may know ozone mainly from the hole in the ozone layer. We find the ozone layer in a higher part of our atmosphere: the stratosphere. Stratospheric ozone is created naturally: because oxygen molecules are split by ultraviolet radiation. Up there in the atmosphere, ozone is critical; it blocks some of the harmful UV rays from the sun. But ozone also occurs lower in the atmosphere. And there it can be dangerous – in high concentrations. Ozone also forms lower in the atmosphere in a different way than in the stratosphere; the substance is born when air pollutants are broken down under the influence of sunlight.

The researchers soon discovered that when they exposed people to ozone in a confined space, something remarkable happened: nanocluster aerosols were formed. “These are tiny particles with a diameter of less than 3 nanometers. “They play an important role in the climate and also affect human health,” study researcher Dusan Licina said. Scientias.nl. “To date, they have mainly been studied outdoors and have been associated with vehicle exhaust emissions. But recently it has been shown that they can also arise indoors.” For example, when people light a candle or cook. But now we can add a new source to that: ourselves.

squalene

The experiments show that our skin, when it is exposed to ozone indoors, also produces these nanoparticles. “Ozone likes to react with different substances indoors, especially with substances with double carbon bonds,” explains Licina. “Squalene – a component of human skin oil – has six of those double bonds. This means that ozone is very reactive with squalene. And during that reaction, nanocluster aerosols are created.”

How does ozone get into the house?
We described above how ozone is created lower in the atmosphere: because pollutants in the air are broken down under the influence of ultraviolet light. This means that ozone is mainly formed in the spring and summer. But how does it end up indoors? “There are two main sources of ozone in buildings,” Licina said. “First of all, ozone can enter from outside through intentional or unintentional ventilation. This is usually the main source of ozone indoors. In addition, some electrical appliances can also generate ozone.” The experiments used an ozone concentration of 40 ppb (parts per billion). “That’s pretty much the upper limit of what we can encounter indoors,” says Licina. “But in other situations, such as in airplanes, the ozone concentration can rise even further.”

Teens

During the experiments, the scientists called on people of different ages. One test subject also showed more skin than the other. The experiments reveal that people with more exposed skin also produce more nanocluster aerosols. In addition, teenagers appear to produce more nanoparticles in the ozone-filled chamber than young adults and the elderly. The researchers are not yet able to properly explain the latter.

health effects

It is also still unclear whether the nanoparticles that our skin produces in the presence of ozone can be harmful. “These particles could grow into larger particles that are associated with health problems caused by the ability of these larger particles to penetrate deep into the lungs and even end up in the brain,” Licina said.

The research clearly raises many new questions. “We used to think that people only emitted particles through their breathing (for example, by sneezing or coughing, ed.) or because particles came off their skin or clothing. But now we have found another mechanism by which humans can generate nanoparticles. It is a first step towards new studies.” For example, the researchers are curious to what extent these ’emissions’ are influenced by the ozone concentrations. “It is also interesting to find out whether the fingerprints we leave behind when we touch objects also contribute to these emissions.”