The working life of a filter depends on many factors such as the pollution level in your surroundings. On average our filters last 100 hours but we advise changing every second week for hygienic reasons, see the figure below as a reference for expected life span of the filter.

Remove and replace the filter if it becomes wet, damaged, contaminated or breathing becomes difficult. 

The filter lasts up to 5 years if it's kept in the provided sealed storage bag, and protected from sun exposure.