Did it ever occur to you how many chemicals you are exposed to, whether at home, at work or in transportation, about the sources of these chemicals and how you can protect your health from their dangers?
External pollutants that make their way indoors, gas emissions from building materials and furnishings, the products of our activities such as cooking and cleaning, and even our bodies;
All of these and more are sources of chemicals that enter the indoor air of our indoor surroundings.
Atmospheric and indoor cleaners
The components of nature play a role in cleaning these chemicals. In the open air, for example, rain through chemical oxidation disinfects the air, as “hydroxyl radicals” largely do this chemical cleaning, so these highly reactive molecules are called “sheath cleaners.” Atmospheric”, which is formed mainly when ultraviolet rays emitted from the sun interact with ozone and water vapor.
In enclosed spaces, where the air is less affected by direct sunlight and rain, and because ultraviolet rays are largely filtered by glass windows, scientists have long assumed that the concentration of hydroxyl radicals is much lower inside the walls than outside, and that the ozone that escapes From outdoor to indoor it is the main oxidizer for airborne chemical pollutants.
In a new study published in the journal Science, a team of scientists led by the Max Planck Institute for Chemistry, in collaboration with researchers from the United States and Denmark, discovered that high levels of hydroxyl radicals can be generated indoors. Simply because of the presence of humans and ozone.
“The discovery that we humans are not only a source of to reactive chemicals, but we are also able to convert these chemicals ourselves, which was very surprising to us."
"The strength and shape of the oxidation field is determined by how much ozone is present, where it is leaking out, and how the ventilation of the interior space is configured."
Hydroxyl radicals (OH) purify the air (websites)
High levels of hydroxyl
The press release states that the hydroxyl levels that the scientists found were comparable to levels of hydroxyl concentrations in the daytime, and that the oxidation field is formed through the interaction of ozone with oils and fats on our skin, especially unsaturated triterpene squalene, which makes up about 10% of the skin lipids that protect our skin. It maintains its freshness, as this reaction releases a group of chemicals in the gas phase that contain double bonds that react further in the air with ozone to generate large levels of hydroxyl radicals.
The study experiments were conducted at the Technical University of Denmark in Copenhagen, where 4 people - subjected to the test - remained in a special climate-controlled room under standard conditions, then ozone was added to the room air flow in an amount that was not harmful to humans but represents higher levels indoors. The team determined hydroxyl values before and during the volunteers' stay, with or without ozone.
In order to understand what the human-generated hydroxyl field looks like during experiments, the results of a detailed multiphase chemical kinetic model from the University of California, Irvine were combined with a computational fluid dynamics model from Penn State University. After validating the models against the experimental results, the modeling team examined how Human-induced hydroxyl domain varied under different conditions of ventilation and ozone, and the results showed that hydroxyl radicals were present in abundance and form strong spatial gradients.
“Our modeling team is the first and currently the only group that can integrate chemical processes between skin and indoor air, from molecular to room scales,” Manabu Shiraiwa, a professor at the University of California, Irvine who led the modeling department, said in the press release. “The model gives meaning to the measurements; It answers the question of why hydroxyl is generated from interaction with the skin."
Shiraywa added that there are still unanswered questions, such as the way humidity levels affect the team's responses. "I think this study opens a new avenue for indoor air research," Shiraywa added.
Modeling the hydroxyl reaction (left) and hydroxyl concentration (right) around our bodies within walls (University of California, Irvine)
Development of methods for testing furniture and building materials
“We need to rethink the inner chemistry of occupied spaces because the oxidation field we create will transform many chemicals in our immediate vicinity,” project leader Jonathan Williams also says in the statement. Hydroxyl can oxidize many more species than ozone, resulting in many more products. directly in our breathing area whose health effects are as yet unknown."
"This oxidation field will also affect the chemical signals we emit and receive, and may help explain the recent finding that our sense of smell is generally more sensitive to molecules that react faster with hydroxyl," Williams adds.
These results directly affect our health, and it is important to test the chemical emissions of many materials and furnishings separately before agreeing to sell them, and it is also advisable to conduct tests in the presence of people and ozone, says Williams, because oxidation processes can lead to the generation of respiratory irritants such as 4-oxopentanal and other oxygen species from hydroxyl radicals, small molecules in the immediate vicinity of the respiratory tract, which can have adverse effects, especially in children and the elderly.