Yes the filters do need replacing.
1. The effective working life of the City™ filter depends on a number of factors, such as; the breathing rate of the user; ambient levels of pollution; the length of time the filter is actively working; hygiene levels. Taking these factors into account we recommend that the filter should be replaced every month or every 69 hours, whichever is sooner.
2. Replacement of the Sportsta™ filter should be carried out every month or when the filter becomes noticeably discoloured.
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