Ozone is safe to use around humans as long as you have the correct concentrations and use for a safe period of time. The chart below shows the details:
| Concentration(ppm) | Duration ofExposure | Effect | |
| ACCEPTABLE | 0.01-0.04 | – | Odor threshold. |
| ZONE | 0.1 | – | Minor eye, nose and throat irritation. |
| 0.1 | 8 hour average exposure limit | ||
| >0.1 | few minutes | Continuous headache, shortness of breath. | |
| 0.25-0.5 | 2-5 hours | Reduction in lung function and the ability to do physical work (for persons with a history of heart or lung disease). | |
| 0.3 | 15 minute exposure limit | ||
| 0.4 | 2 hours | Reduction in lung function during moderate work for all persons. | |
| HAZARDOUS | >0.6 | 1-2 hours | Chest pain, dry cough. |
| ZONE | 1 | 1-2 hours | Lung irritation (coughing), severe fatigue. |
| >1.5 | 2 hours | Reduced ability to think clearly. Continuing cough and extreme tiredness maybe lasting for 2 weeks.Severe lung irrituation with fluid build-up. | |
| 9 | intermittent | Severe pneumonia (arc welders). | |
| 10 | Immmediately dangerous to life & health | ||
| CRITICAL | 11 | 15 minutes | Rapid unconsciousness. |
| ZONE | 50 | 30 minutes | Expected to be fatal. |