Nitrogen is the most abundant gas in air (near 80%), and second is oxygen (about 20%). In fact, our organism only takes oxygen for being transported in the bloodstream. We also are carbon dioxide producers because once oxygen is consumed the body breathes out CO2.
Take care of aerating where you live! Although if the window is only the path to get heavy traffic pollution, please think in another method.
It's curious that only 0.00005% is hydrogen because this element stays considerably abundant in other setups. It is believed to be the more abundant one in the entire Universe. Sun would have in the photosphere about 72%. Helium, the second more present in the Universe also has an insignificant 0.0005% in common air inside our big blue home.
There is a gas called argon that is even more abundant (0.9%) than carbon dioxide (0.03%). Then, it deserves a closer look as surpasses the very known CO2. Argon is called a noble gas, with the third place in air composition and usually used in industrial processes where an "inactive" element is needed.
That's the meaning of Argon in Greek ... inactive. If we are breathing this gas each day, we could suppose that is not very toxic, nevertheless in high concentration could be fatal. This gas is being used as artificial atmosphere when growing crystals of the two materials primarily used in semiconductors, silicon and germanium. Who said computers?
An adult person has an average respiratory rate of 12 to 24 breaths in one minute and we are also interacting at that rate with other rare air elements with captivating names like xenon or krypton. There's more, but always remember that oxygen is the main interest for us... where the healthy atmosphere comes into play.
Other compounds could simply be more an issue than a benefit like the ones that come from pollution.