Ozone, written chemically as O3, was first discovered by the Dutch physicist Martin van Marum. His research was furthered by the Swiss-German chemist, Christian Friedrich Schönbein, who gave the compound the name “ozone”. In the roughly 250 years since its discovery, ozone has become a topic of intense research. O3 plays an important role in our environment and atmosphere, acts as an important industrial reagent, and has a variety of medicinal uses. Today, let’s take a moment to better understand this important chemical: what is ozone?
Chemistry of Ozone
Ozone is a molecule composed of three oxygen atoms connected together in a line. The vast majority of ozone, roughly 90%, is located in our stratosphere, approximately 10-50 km above the Earth’s surface. Ozone is created naturally in our environment. UV rays from the sun can split the oxygen we breathe, O2, into single oxygen atoms. These single oxygen atoms can then join together to reform O2 or join with an existing O2 molecule to form O3, ozone.
Uses for Ozone
Since its discovery in the mid-19th century, the number of known benefits of ozone has expanded greatly. O3 is an important factor in our atmosphere, industry, medicine, and sanitation.
Ozone plays a very polarizing role in our atmosphere. The United States Environmental Protection Agency (EPA) uses the phrase “good up high, bad nearby” to explain this. As previously stated, the majority of our ozone occurs in the stratosphere. This is the “good up high” ozone. This ozone protects planet Earth by blocking a significant portion of the UV light that originates from the sun. Without this ozone, Earth would effectively be sterilized.
This is the same ozone that comes up in discussions of climate change. This protective “blanket” of ozone is gradually destroyed by a variety of human made compounds. These are typically classed as ozone-depleting substances (ODS) and they contribute to the “ozone hole.”
While the “good up high” ozone serves to protect Earth, the ‘bad nearby’ ozone functions as a pollutant. This ozone is formed through a specific suite of chemical reactions that involve fossil fuel emissions. Volatile compounds, those that evaporate easily, react with a gas called nitrogen oxide, which is a byproduct of vehicle and industrial emissions. The end result is ozone, and when it is produced that low to the ground, it is considered a pollutant.
A variety of industries across the world have adopted ozone as an important reagent or component in their industrial processes. The pharmaceutical industry uses ozone as a reactant to produce some very common steroid drugs, including cortisol. While not as common in the United States, a variety of European countries use ozone to treat and disinfect their water.
Ozone is implicated in the treatment of a wide variety of diseases. According to a 2011 review of literature, ozone has been used to treat “ infected wounds, circulatory disorders, geriatric conditions, macular degeneration, viral diseases, rheumatism/arthritis, cancer, SARS and AIDS.”
Ozone has been shown to accomplish three separate medicinal goals. First, it can inactivate fungi, viruses, bacteria yeast and protozoa. O3 does this by disrupting their cell membranes and interrupting important cellular processes. This effect was known back in WWI, where, in the absence of other antibiotics, field doctors used topical ozone to treat infected wounds.
In the last quarter century, ozone has emerged as a powerful new way to disinfect a variety of contaminated surfaces. A 2017 study conducted by the University of Siena, Italy, concluded, “Aqueous and gaseous ozone treatments were effective against microbial contaminants...these results confirm the efficacy of the ozone disinfection treatment of both water and air.” In light of this and other research, sanitation via O3 has been adopted to sanitize food packaging, kitchen exhaust, and CPAP machines.
Is Ozone Safe?
Like almost all compounds, the key to understanding danger or efficacy is through dosage. For example, 600mg of ibuprofen can relieve a headache, but a whole bottle can send a patient to the emergency room. Likewise, “an apple a day keeps the doctor away”, but the combined dosage of 40 apples (and their seeds) can be deadly to humans.
Ozone is no different. In small, medicinal dosages, O3 is a very important treatment option. In larger quantities, it can have significant health risks. One way scientists measure the dosage of ozone is on a scale of parts per million (ppm) or billion (ppb). In our upper atmosphere, the stratosphere, concentrations can be as high as 15 ppm. Down low, in the troposphere, concentrations usually hover around 10 ppb.
The EPA established a safe threshold of 70 ppb in 2015. They indicate that exposure to concentrations above this for more than 8 hours at a time can be hazardous to your health. These dangerous conditions are typically only found in cities where the temperature is warm and stable. Health risks include “throat and lung irritation or aggravation of asthma or emphysema.” The FDA has established its own standard of 50 ppb.
Ozone: Final Verdict
Ozone has been an important chemical for human use for nearly 200 years. Since its discovery, O3 has been used in countless aspects of human life: medicine, sanitation, industry. With the proper research and guidelines, we can continue to utilize this multifaceted compound for our benefit.
Written by: Patrick O'Hare