How long can the mask be used for?
Cambridge Masks‚ are non-disposable, meaning that you can use them for potentially 340 hours of active use, or 6 months of daily use during a commute or other activity. The length of time they are suitable for depends on how polluted the environment is when you use it.
A general guideline is that you can use the masks on a regular basis for 3-6 months before it needs replacing. Once the mask is past its useful life a new mask is needed. A table is provided below.
| Pollution Level | Air Quality Condition (AQI) | Description | Replace after |
| Good | Below 50 | Clear visibility to horizon | Mask not needed |
| Moderate/Unhealthy for Sensitive Groups | 51 - 150 | Cannot see pollution with the naked eye, slight haz on horizon | 340 hours |
| Unhealthy/Very Unhealthy | 151 - 300 | Haze at 2-3km visibility | 220 hours |
| Hazardous | 301 - 500 | Clouds of pollution, visibility around 1km | 180 hours |
| Beyond Index | Above 500 | Visibility below 600 meters. Fog-like clouds of Pollution clearly visible even in bright sunlight | 90 hours |