The newly discovered substance is extremely oxidizing. And so scientists suspect that the effects of this substance could be far-reaching.

Our atmosphere is made up of many compounds and elements. Well-known are of course oxygen and nitrogen, but we also find reactive chemical compounds, such as hydrogen peroxide. Now researchers have discovered a completely new class of such a reactive substance in our Earth’s atmosphere. And it’s one to keep an eye on.

Peroxides

It is a super-reactive substance that the researchers have called hydrotrioxides (ROOOH). And this compound is even more reactive than peroxides. That’s right. All peroxides – including hydrogen peroxide – consist of two adjacent oxygen atoms. This makes them very reactive, flammable and explosive. They are used for everything; for whitening teeth and hair, cleaning wounds and even as rocket fuel. But peroxides are also present in our surrounding air.

Trioxides

In recent years there has been speculation about so-called ‘trioxides’: chemical compounds with not two, but three oxygen atoms attached to each other. As a result, these compounds are even more reactive than peroxides. Some scientists think that our atmosphere also harbors such trioxides, but this has never been proven. Until now.

Hydrotrioxides

In the new study researchers have proven the existence of such a trioxide. And they call this super-reactive substance hydrotrioxides. It is a completely new class of chemical compounds that are formed under atmospheric conditions. “The type of compounds we’ve discovered has a unique structure,” said researcher Henrik Grum Kjærgaard. “And because they are extremely oxidizing, they most likely have a host of as-yet-unknown effects.”

When chemical compounds in the atmosphere oxidize, they often react with OH radicals, forming a new radical. When this radical reacts with oxygen, it forms a third radical called peroxide (ROO), which in turn can react with the OH radical. This is how hydrotrioxides (ROOOH) are formed. Image: University of Copenhagen

Hydrotrioxides are formed in a reaction between two types of radicals. The researchers expect that almost all chemical compounds form hydrotrioxides in the atmosphere. Their lifespan is believed to range from minutes to hours. This makes them stable enough to react with many other atmospheric compounds. In addition, the researchers showed that hydrotrioxides are formed during the atmospheric breakdown of several known and widely emitted substances, including isoprene and dimethyl sulfide.

Isoprene is one of the most abundant organic compounds in the atmosphere. The research shows that about 1 percent of all released isoprene is converted into hydrotrioxides. The researchers estimate that the ROOOH concentrations in the atmosphere are about 10 million per cm3. In comparison, OH radicals, one of the major oxidants in the atmosphere, are found in about 1 million radicals per cm3.

The researchers suspect that hydrotrioxides affect both human health and our global climate.

Health

The research team thinks that the trioxides can penetrate into small particles in the air, known as aerosols, which pose a health hazard and can lead to respiratory and cardiovascular diseases. “Hydrotrioxides most likely end up in aerosols, where they form new compounds with new effects,” says Kjærgaard. “It is therefore likely that new substances are formed in the aerosols that are harmful when inhaled. But further research is needed to confirm these potential health effects.”

climate

In addition, according to the researchers, there is a good chance that hydrotrioxides influence the number of aerosols that are produced. And in that way, the newly discovered compound also affects our climate. “Sunlight is both reflected and absorbed by aerosols,” explains researcher Eva Kjærgaard. “And that in turn influences the heat balance (i.e. the ratio of sunlight that the earth absorbs and sends back to space). When aerosols absorb substances, they grow and contribute to cloud formation, which also has consequences for the Earth’s climate.”

Effects

The researchers hope the discovery of hydrotrioxides will help us learn more about the effects of the chemicals we emit. “Most human activities lead to the release of chemicals into the atmosphere,” said researcher Kristan Møller. “So knowledge of the reactions that determine atmospheric chemistry is important in predicting how our actions will affect the atmosphere in the future.” And so the study is an important step forward. “It’s very important that we can now show by direct observation that hydrotrioxides actually form in the atmosphere, that they are surprisingly stable and that they are formed from almost all chemical compounds,” said researcher Jing Chen.

To care

While the effects of hydrotrioxides in air can be far-reaching, the researchers aren’t really concerned about their discovery. “These connections have always been there – we just didn’t know about them yet,” says Grum Kjærgaard. “But now that we have evidence that the compounds are formed, we can study their effects in a more targeted way. And then we can also react if they turn out to be dangerous.”

The discovery suggests that there may be even more undiscovered compounds and elements hidden in the air we breathe. “The air around us is a maze of complex chemical reactions,” Chen says. And with the study, the researchers have at least taken a step to really untangle things.