The air we suck down is mostly made up of nitrogen, with a generous helping of oxygen, and a dash of carbon dioxide.
We can only speculate about some of the compounds and elements that are in this soup.
One of the mysteries came into focus. Chemists have shown that a class of compounds called organic hydrotrioxides exist in the atmosphere, and while they last only a short time, they could have effects we don't know about.
The researchers calculated that you took up a few billion molecules of them while reading this.
Exactly what this means for your health, not to mention the health of our planet, is up in the air. It is worth looking into, given that we have just discovered this new ingredient in Earth's atmosphere.
"These compounds have always been around, we just didn't know about them." says Chemist Henrik Grum Kj.
It is possible to study the effect of compounds if they turn out to be dangerous, because we now have evidence that they are formed and live for a certain amount of time.
In chemistry, the addition of a single new component can change how a material behaves.
For example, take water. Organic chemistry can mix and swirl into an evolving phenomenon we call life, thanks to the way its pair of hydrogens and single oxygen interact.
Adding just one more oxygen can cause hydrogen peroxide to tear living chemistry apart.
The result is hydrotrioxide, if you stick one more oxygen onto it. To make it, you need the right equipment, some saturated organic compounds, and some dry ice.
It is not the kind of party trick you would use to liven up a margarita, but chemists have used it to make various other substances.
Being highly reactive, there is an open question as to whether hydrotrioxides can form stable structures in the atmosphere.
It is also an academic point of speculation. The way trace materials interact with each other in our atmosphere has a huge impact on how our atmosphere operates.
Most human activity causes emission of chemical substances into the atmosphere. 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.
The first direct observations of hydrotrioxide forming under atmospheric conditions from several substances known to be present in our air have been provided by the team.
They were able to study how the compound is likely to be synthesised, how long it sticks around for, and how it degrades.
10 million metric tons of hydrotrioxide can be generated each year by one emission called isoprene.
That is just one possible source. According to the team's calculations, just about any compound could play a role in the atmospheric formation of hydrotrioxides, which remain intact for anywhere between a few minutes to a few hours.
In that time, they can participate in a number of other reactions as a powerful oxidant, some of which could be sheltered inside tiny particles drifting on the winds.
It is easy to imagine that new substances are formed in the aerosols. Further investigation is needed to address the potential health effects.
Knowing how aerosols grow or degrade could change how we model our climate.
The role hydrotrioxides play in the atmospheric cocktail will be examined further. It is just the beginning according to University of Copenhagen researcher Jing Chen.
Chen says the air surrounding us is a huge tangle of complex chemical reactions.
If we want to get better at finding solutions, we need to keep an open mind.
Science has published this research.