Ozone is a toxic gas, after inhalation it can cause sickness if inhaled in sufficient quantity.
Humans can stand a limited exposure of ozone, symptoms like dryness in the mouth and throat, coughing, headache and chest restriction can occur and nearby the lethal limits, more acute problems will follow in a higher concentration.
* 0,06 PPM for 8 hours a day, 5 days a week (PPM = Parts Per Million)
* 0,3 PPM for maximum 15 minutes
These limits are a Maximum Acceptable Concentration (MAC), these concentration are much higher than the odor threshold at which ozone can be smelled.
Ozone spontaneously decomposes under all ordinary conditions, so that is not normally encountered except in the immediate vicinity of its production. Decomposition is accelerated by contact with solid surfaces, by contact with chemical substances and by the effect of heat.