Ozone exists in very low concentrations throughout the atmosphere but is concentrated in the lower part of the Stratosphere. Often referred to as the Ozone Layer, Ozone in the lower stratosphere reduces the amount of damaging ultra violet light that reaches the Earth’s surface.
Health Effects of Ozone
Ozone is poisonous and, in high enough concentrations, can cause headaches, irritation to the respiratory system, and can harm lung function.
Aircraft flying above the Tropopause may therefore be flying through air with high concentrations of Ozone. Catalytic converters are fitted to the aircraft air conditioning systems on most modern aircraft to break down the Ozone into harmless Oxygen.