Always change both carbon and dust filters at the same time
Always store the gas mask in a sealed plastic bag when not in use
The lifespan of the filter is affected by many factors - how big and what type of contaminants, breathing rate, humidity, ventilation, temperature, etc.
Replace both filters when:
The expiry date on the packaging has passed
Maximum usage time is 6 months after opening, regardless of whether the filters are used or not as they absorb contaminants in the environment