The Terribly Fresh Smell of Ozone

Our noses have snuffed up the fresh smell after a thunderstorm, clean laundry, and well-aerated water ever since creation; but we were not aware that a simple combination of three oxygen atoms was responsible for these delightful odors until Christian Friedrich Schönbein zeroed in on this fact in the later 1800’s. The peculiar odor was noted by the Dutch scientist Van Muram in 1801 when he ran his electrostatic generators. He called it “the smell of electricity.” Schönbein’s experiments with electrolysis also generated some ozone. Although this odor was not the focus of his studies, he could not resist investigating the source of this smell. He felt close enough to finding this substance to give it a name. For this he turned to the language of the insightful and descriptive Greeks.

Scanning through the various forms of “smell” in a good Greek dictionary for a suitable name, he came across the verb form ὄζω which sounds like “odzo” and translates “I smell” as in, “I smell the rain.” The root word in Greek for smell is ” ὀδ” from which the English word “odor” is derived. Typically you read that the word “ozone” comes from the infinitive form ὄζειν “to smell,” but I would like to suggest he was attracted to the genitive form “ὄζων” which sounds most like the German “ozon” and the English “ozone.” The genitive form is used to express the idea of source, and is used in Greek texts to mean “that from which the smell comes.”

“Ozone.” The word fit well. The ancient Greek poet Homer, reciting his epic poem “The Iliad” about 1000 years before Christ said,

“As an oak falls headlong when uprooted by the lightning flash of God,
And there is the terrible ozone of brimstone –
No man can help being dismayed if he is standing near it
For a thunderbolt is a very awful thing –
Even so did Hector fall to earth and bite the dust.
Homer, The Illiad, Book XIV

Here Homer connects the odor of ozone with lightning and its awful power. Instead of translating the Greek word “ὄζων” as “smell”, I have simply transliterated the sound of the Greek word directly to “ozone.” Schönbein’s name for this substance was an excellent choice, having a few thousand years of historical precedent for naming this important molecule.

A variety of careful observations about the circumstances of ozone production and its effect on other substances brought Schonbein closer to understanding the precise composition of ozone. Eventually in 1865 another man, Jacques-Louis Soret, determined the precise formula for ozone as O₃. Experiments with ozone exposed some of the harmful effects of high ozone levels to plant and animal health, but also led to the realization that ozone could be used to disinfect polluted water. It became clear that with proper use, ozone could be a powerful tool for healthy living. The fresh, invigorating, clean smell of a tiny pinch of ozone is our hint to ozone’s helpful qualities.

A little dose of bright sunshine on our skin is good for the body. It is healthy and we are attracted to it, but too much can burn and cause harm. So it is with ozone. Just like fire or electricity, its power must be respected and put to precise and careful use. We need a gentle flow of electrons through our nervous system to think and direct our bodies, but need protection from the power of electricity in the world around us.

How much is too much? At about the time the smell of ozone becomes distinctive, it is time to be aware of its source and the potential for dangerous levels of ozone. With an increase in concentration, it turns quickly to a pungent suffocating smell. At that point it is time to limit breathing exposure to avoid oxidation of sensitive lung tissue. Only a good quality ozone sensor that is up to date with calibration will give accurate measurements of ozone levels. OSHA requires that workers not be exposed to ozone levels over 0.1 ppm ozone over the course of 8 hours.

Ozone as the “smell of electricity” could also be described as “the smell of energy.” Ozone is oxygen that has been infused with a tremendous amount of energy. When that energy is released, it causes physical damage to small sensitive things like bacteria, viruses, and sensitive lung tissue. The fresh smell of ozone after a thunderstorm is our reminder that big powerful things are happening to bring refreshing rain. A hint of ozone smell in a water bottling plant can make you confident that the water is free of harmful pathogens.

Ozone is a very valuable form of oxidizing energy with countless uses. Dissolved in water, ozone retains its power to disinfect, but does not come into contact with the sensitive tissue of your lungs. It is safe to handle ozonated water provided any ozone off-gassing is limited or safely removed. Dissolved ozone is like electricity in a shielded wire where it is safe and useful. Those who build and operate machines that harness the power of ozone must understand and respect the power of ozone as well as the rules and regulations that have been put in place for the safe use of ozone.