Indoor ozone pollution causes the human body to produce hydroxyl radicals

Indoor ozone pollution causes the human body to produce hydroxyl radicals

Exposure of the human body to ozone indoors produces highly reactive hydroxyl (OH) radicals, which are largely responsible for the oxidation of most pollutant gases, researchers report. The results have implications for our understanding of the role of humans in indoor air chemistry and quality. “[The authors] observed that the human body interacts with the indoor environment in a similar way that the Earth interacts with the atmosphere,” write Coralie Schoemaecker and Nicola Carslaw in a related Perspective.

“Both the human body and the Earth are chemical reactors that consume or produce oxidants and oxidized species in their surrounding atmosphere.” The vast majority of people spend most of their time indoors - whether at home or at work or while traveling between the two - and are exposed to a range of chemicals from a variety of sources, including outdoor pollutants that get indoors, as well as gaseous emissions from building materials and furnishings, and products from activities such as cooking and cleaning. In addition, the human body is also a potent mobile source of emissions.

The chemical removal of gaseous pollutants in outdoor air during the day is primarily driven by the production of OH radicals, formed primarily by the photolysis of ozone by ultraviolet sunlight. However, the quality of indoor air is much less affected by this process because glass windows largely filter out ultraviolet light. While research has shown that some OH radicals can be generated in other ways indoors, few studies have examined the chemical impact on the human body in these environments.

Through a series of experiments, Nora Zannoni and colleagues found that high concentrations of OH radicals were generated when people were exposed to varying concentrations of ozone in a climate-controlled stainless steel chamber. According to Zannoni et al. Squalene co-reacted in skin oil to produce 6-methyl-5-hepten-2-one (6-MHO), which was key to establishing this man-made oxidation field. In addition, they found that isoprene from human breath and products of its interaction with OH also react with ozone to produce more OH radicals, suggesting that humans are a net source of reactive oxidants indoors.

Source:

American Association for the Advancement of Science (AAAS)

Reference:

Zannoni, N., et al. (2022) The human oxidation field. Science. doi.org/10.1126/science.abn0340.

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