"The discovery suggests that there could be plenty of other things in the air that we don't yet know about. But the fact that we now have evidence that the compounds are formed and live for a certain amount of time means that it is possible to study their effect more targeted and respond if they turn out to be dangerous," says Henrik Grum Kjærgaard. "These compounds have always been around – we just didn't know about them. However, neither he nor Henrik Grum Kjærgaard are worried about the new discovery: So, knowledge of the reactions that determine atmospheric chemistry is important if we are to be able to predict how our actions will affect the atmosphere in the future," says co-author and postdoc, Kristan H. "Most human activity leads to emission of chemical substances into the atmosphere. The researchers hope that the discovery of hydrotrioxides will help us learn more about the effect of the chemicals we emit. Compound’s effect needs to be studied further When aerosols absorb substances, they grow and contribute to cloud formation, which affects Earth's climate as well," says co-author and PhD. "As sunlight is both reflected and absorbed by aerosols, this affects the Earth's heat balance – that is, the ratio of sunlight that Earth absorbs and sends back into space. And according to the researchers, there is a high probability that hydrotrioxides impact how many aerosols are produced. While aerosols also have an impact on climate, they are one of the things that are most difficult to describe in climate models. But further investigation is required to address these potential health effects," says Henrik Grum Kjærgaard. It is easy to imagine that new substances are formed in the aerosols that are harmful if inhaled. "They will most likely enter aerosols, where they will form new compounds with new effects. The research team also has the trioxides under strong suspicion of being able to penetrate into tiny airborne particles, known as aerosols, which pose a health hazard and can lead to respiratory and cardiovascular diseases. This makes them stable enough to react with many other atmospheric compounds. The researchers expect that almost all chemical compounds will form hydrotrioxides in the atmosphere and estimate that their lifespans range from minutes to hours. Hydrotrioxides are formed in a reaction between two types of radicals (see fact box). All speculation must now be put to rest," says Jing Chen, a PhD student at the Department of Chemistry and second author of the study. "It’s quite significant that we can now show, through direct observation, that these compounds actually form in the atmosphere, that they are surprisingly stable and that they are formed from almost all chemical compounds. The researchers have also shown that hydrotrioxides are formed during the atmospheric decomposition of several known and widely emitted substances, including isoprene and dimethyl sulfide. Researchers at the University of Copenhagen (UCPH), together with colleagues at the Leibniz Institute for Tropospheric Research (TROPOS) and the California Institute of Technology (Caltech), have demonstrated that these compounds are formed under atmospheric conditions. Hydrotrioxides (ROOOH), as they are known, are a completely new class of chemical compounds. And, because they are extremely oxidizing, they most likely bring a host of effects that we have yet to uncover." "The type of compounds we discovered are unique in their structure. Kjærgaard is the senior author of the study, just published in the prestigious journal, Science. "This is what we have now accomplished," says Professor Henrik Grum Kjærgaard, at the University of Copenhagen’s Department of Chemistry. ![]() ![]() But until now, it has never been unequivocally proven. In recent years, there has been speculation as to whether trioxides – chemical compounds with three oxygen atoms attached to each other, and thereby even more reactive than the peroxides – are found in the atmosphere as well. But peroxides are also found in the air surrounding us. They are used for everything from whitening teeth and hair, to cleaning wounds and even as rocket fuel. All peroxides have two oxygen atoms attached to each other, making them highly reactive and often flammable and explosive. Researchers from the University of Copenhagen, in close collaboration with international colleagues, have documented the formation of so-called trioxides – an extremely oxidizing chemical compound that likely affects both human health and our global climate.Ī commonly known chemical compound is hydrogen peroxide. Image: Reaction: ROO + OH → ROOOH (oxygen atoms in red) view moreĬredit: University of Copenhagen For the first time, an entirely new class of super-reactive chemical compounds has been discovered under atmospheric conditions.
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