Ozone concentration limiting?


Hi fellow aviators, I’ve been studying my AOM (Legacy)recently and there are a few pages about ozone concentration limits in there. The table shows the highest flightlevels (dependant on location) at which the aircraft can be safely flown at over a certain period of time.
Is this more of a human factor limitation or aircraft limitation? I can’t imagine it has anything to do with the aircraft. Anyone knows?

Please help.

I didn’t find the right solution from the Internet.

References: http://www.flightwork.com/pilot-forum/posts/tech_talk/ozone_concentration_limiting.html

Commercial Link deleted by moderator


You are asking these questions on a non member guest forum which most members ignore because they are on the pay side. I’m not sure you are going to get a timely answer to your questions this way on this forum. I’m not saying to join to have the, answered, but consider the audience and questions you are asking.


It has nothing to do with aircraft performance. Ozone actually shields human beings from ionizing radiation coming from outer space. The higher you fly, the less ozone exists thereby limiting that protective part of our atmosphere. Humans that fly too high too often are vulnerable to excess radiation exposure.

Actually, higher concentrations of ozone is found above FL350 than on the surface. Airliners have ozone scrubbers to help alleviate ozone sickness. Airline companies issue ozone alerts to avoid pockets of high ozone concentrations.

Ozone is a variant of oxygen produced by the action of solar radiation on high altitude oxygen.

It is a toxic gas that damages the lungs by irreversibly destroying the elasticity of the lung tissue (emphysema).

Little ozone is present in the troposphere but concentrations rise rapidly above the tropopause increasing with altitude (greatest concentrations in winter and spring)

As the tropopause is much lower over the poles the risk from the effects of ozone is greatest on trans-polar flights.

Thus Ozone is a potential danger between 40,000 and 75,000 ft.

Symptoms of ozone poisoning are dryness of the nose and throat with irritation causing coughing and a discomfort in the chest.

Severe poisoning can cause breathing difficulties, heart strain and sometimes death.

Concentration of ozone is more significant than its exposure time.

FAA concentration limit is 0.25 parts per million by volume (ppmv) for commercial flights.

Ozone is partly destroyed by the high temperatures created in the compressors of jet engines.

Aircraft with lower compressor temperatures require catalytic converters and carbon filters to reduce the ozone concentration to an acceptable level.

Higher cabin humidity reduces the severity of the symptoms of ozone poisoning.

Ozone is usually destroyed by the pressurisation process.

[:O]Hmmmm. Then does that make these things dangerous?


The Ozonics HR300 Scent Elimination Unit boasts up to 45% more ozone output than the HR200 for more odor-stopping power, and it has a quieter fan for silence in the field. Integrated Pulse Technology regulates time and oxidant concentration, ensuring the proper amount of ozone is being deployed at all time.


Get the competitive edge. The Hunter’s Closet provides an easy and effective way for hunters to eliminate all odors on clothing and equipment so you are ready for the next hunt. The digital generator emits a chemical free ozone that starts destroying odors within 30 minutes. The closet is easy to assemble and tough enough to use outdoors. Shelves are convertible and adjustable to suit your storage needs; great for basements, garages & hunting camps.

The amount of ozone produced by a ozone generator is insignificant to the normal atmosphere we live in. Closing the closet doors allow higher concentrations. Excess ozone quickly converts back to oxygen when the doors are opened. Note: do not breathe concentrated ozone gas. Don’t let your kids play in the closet if you have one installed.

If you have a cabin full of sick passengers coughing and such, can you turn the scrubbers off to clean the cabin? :wink:

I had a car dealer client who swore by his ozone generator cleaning up smokers cars and oder problems. They close it up inside and let it run for a day or three.


If they are coughing and wheezing because of excess ozone, you would want the scrubbers on. [;)]

The answer is the system is autonomous and out of my control. We receive messages from metro informing us if the ozone concentration levels along our route of flight is greater than our scrubbers can handle. In that case we avoid that area.

I want the ozone if the coughing is from viruses and such vs the ozone itself! I used to inject ozone into a marine aquarium to help scrub it as O3 is a powerful oxidizer :wink:


I learned something today. Fascinating.

I hear you Bryan. The good news is the cabin air is changed out regularly (every 6-7 minutes?). It used to be faster but some of the air is now recycled back into the cabin to reduce bleed air heating requirements.

Just returning the favor, Boss.

Thanks Harry on a lesson about breathing for a lung doctor! Well appreciated!