Ozone: Friend or Foe?

Aug 4, 2010

Depending on who you ask, you may hear ozone described as an air cleaner or a pollutant.  Some people buy machines to purposefully produce it to improve their health, and others avoid it because of the harmful effects on health.  To further confuse matters, we sometimes hear outdoor ozone referred to in a good light (the ozone layer) and other times in a bad light (as a component of air pollution).  In this short blog post, I will cut through the smog so you can better understand ozone.

What is it?

Ozone is also known as activated oxygen, allotropic oxygen, and triatomic oxygen.  It is comprised of three oxygen atoms (O3), whereas atmospheric oxygen is comprised of two oxygen atoms (dioxygen, O2).  Ozone is both naturally occurring and anthropogenic, meaning it is derived from human activities.  Naturally it can occur during a thunderstorm outdoors.  Indoors it is typically found as an incidental by-product of the following:

  • Electrostatic air cleaners
  • Photocopiers
  • Laser printers
  • Fax machines
  • Sewing Machines
  • UV Lights
  • Indoor hot tubs

So what is so good about ozone? Ozone can react with contaminants in the air and break them down via an oxidative process.  Ozone has been used successfully for years by professionals who restore smoke damaged personal items embedded with a residual odor.

So what’s so bad about ozone?  Here is a quote from the Environmental Protection Agency (EPA) regarding its health effects:

“The same chemical properties that allow high concentrations of ozone to react with organic material outside the body give it the ability to react with similar organic material that makes up the body, and potentially cause harmful health consequences. When inhaled, ozone can damage the lungs. Relatively low amounts can cause chest pain, coughing, shortness of breath, and, throat irritation. Ozone may also worsen chronic respiratory diseases such as asthma and compromise the ability of the body to fight respiratory infections.”


Ozone producing products should be avoided in spaces that are occupied by people or pets.  Even using these products in unoccupied spaces can have its risks:

  • In the presence of humidity, ozone may produce hydrogen peroxide and stain contents
  • In the presence of some VOCs like limonene and pinene, ozone can produce ultrafine particles
  • As ozone is breaking down organic compounds, intermediate chemicals can be produced that are worse than the originals
  • Ozone can oxidize rubber and soft plastics, damaging appliances and equipment

The final answer: Ozone is usually a foe.