Duncan Aviation logo

How Ozone Affects Passengers & System Components

April 2011

Ozone is a form of oxygen that is found in the upper atmosphere. It can enter the cabin through the air-conditioning system and cause such symptoms as headaches, fatigue, irritation of the eyes, throat and nose, a shortness of breath, coughing and chest pains. These symptoms are often associated with “jet lag” and “air sickness” and can be caused by increased ozone levels in the cabin.
The FAA has mandated that ozone levels in the cabin not exceed .25 PPM sea level equivalent at any time and .1 PPM on any three-hour interval flight. These are the minimum standards set by 14CFR 25.832.

Ozone Converters are devices installed in the ducting that causes ozone to decompose to oxygen before entering the system. Most aircraft that fly above Flight Level 270, or 27,000 feet, have requirements to replace or clean the Ozone Converter. This cleaning process not only keeps the converter operating at a high level of efficiency but also helps prolong the air-conditioning system and components’ life.

Ozone not only has an effect on humans but fluorocarbons as well, such as the seals and gaskets found in many air-conditioning components. High ozone levels can cause these seals and gaskets to become dry and brittle, leading to premature failure. Following the replacement or cleaning interval of the Ozone Converter is extremely important to the well-being of the passengers and system components.