Researchers have shown that certain chemical species produced by our body react with ozone and significantly modify the chemical composition of the surrounding air.
The air around us is loaded with potentially undesirable molecules, whether for humans or for its environment. Some natural processes can rid us of some of them. This is particularly the case of UV radiation emitted by the Sun. And by studying this mechanism indoors, researchers have made a very surprising discovery; in work spotted by Interesting Engineering, they showed that the human body produces its own “ oxidative field ” who directly alters the chemical composition of the surrounding air.
Outdoors, the Sun’s UV radiation reacts with ozone molecules in the atmosphere to form what are called hydroxyl radicals, or OH radicals. It is a chemical species that belongs to the family of free radicals, which means that it has several solitary electrons.
Hydroxyl radicals,atmospheric detergents“
However, the electrons cannot bear to be alone; this configuration makes these free radicals unstable, as these particles desperately seek a mate to pair up with to stabilize the molecule. In practice, this means that these OH radicals are extremely reactive; they combine easily with other chemical species (one speaks of oxidation in this context). In the atmosphere, it is precisely ozone that often serves as a partner for these OH radicals.
This process is very important for humans. These radicals are sometimes referred to as “atmospheric detergents”, because this oxidation tends to neutralize a large number of airborne pollutants… at least outdoors. In fact, glass windows filter a considerable part of radiation that has a short wavelength, such as UV.
The researchers therefore expected that the concentration of OH radicals would be relatively low indoors, which would have direct consequences on air quality and therefore on human health.
To verify this, they therefore set up an experiment based on three groups of four people. They asked them to stay for a while in a special room, deprived of solar radiation and where the composition of the air was precisely controlled.
The human body is an OH radical factory.
They monitored the level of OH radicals there, with and without ozone. And when they compiled the results, a big surprise awaited them; these molecules were indeed present in the air of the room, and in abundance. In some cases, this concentration was even comparable to that which can be measured outdoors.
According to the researchers, there was only one possible interpretation: it was the human body that produced these OH radicals itself. ” The discovery that humans are not only a source of reactive chemical species, but that we can also transform them ourselves has surprised us a lot. “, concedes Nora Zannoni, researcher at the Institute of Atmospheric Sciences and Climate in Italy.
They then tried to find the precise origin of this phenomenon. They determined that the body generates its own oxidation field when ozone in the air reacts with squalene. It is a hydrocarbon produced by mammals; it is essential for the synthesis of certain essential molecules of our physiology, such as steroid hormones, vitamin D or cholesterol.
It is also one of the fatty compounds that help protect the skin, and it is at this level that it reacts with ozone to feed this famous oxidation field. This is also the case for certain compounds present in exhaled air.
No direct danger, but significant implications
This discovery is not bad news in itself. As stated above, OH radicals are extremely unstable and they are not not dangerous as such. But this dynamic could still have significant consequences that must absolutely be explored as a precautionary principle.
Because if the extreme reactivity of OH radicals allows them to neutralize certain pollutants, it also means that they probably react with lots of other chemical compounds. This means that they could perfectly participate in the formation of potentially hazardous substances.
However, the results of all these interactions are still very poorly documented. For researchers, this raises many questions, all of which have direct implications for public health. They therefore believe that we will have to look seriously at the question, even if it means making major changes in the layout of spaces.
This would imply, for example, integrating new tests into the certification procedures that allow a new material to be placed on the market. Indeed, new products are not necessarily tested in the presence of living beings and ozone. These certifications could therefore miss some reactions with free radicalswith potential consequences for human health.
” We need to rethink the chemistry of indoor air, because the oxidation fields we produce will transform many chemical compounds in our direct vicinity concludes Jonathan Williams, lead author of the study.
The text of the study is available here.