As with any product, a slight odour may be noticed in some filters due it its inherent material. We do our best to minimise that smell, and we encourage our customers to reach out to the Blueair Customer Support teams for any questions or needs for support.

More information about filter odour:

New filter
New products may emit an odour when opening the box; that is normal.
All materials, including filter materials, have their smell. The filter is enclosed by a plastic bag and a cardboard box, and the smell from the product accumulates inside. The smell from filter media is harmless.
Run your air purifier and ventilate your room to air out the air purifier and its filter to reduce the new filter odour faster. 
You may also place the new filter by an open window before using it or run your air purifier in a room where you spend less of your time first for a few days until the odour fades away.

Used filter /filter used in a strong odour environment
When the filter is full and gets clogged, it can start to release a smell. To help prevent this, we recommend replacing it based on recommended lifetime.

A recommended lifetime of the filter is stated for each Blueair product; however, the filter lifetime is highly dependent on the environment the air purifier is in, which could require more frequent replacement if you live in a high pollution-prone area (ie, wildfire, sandstorms, pets, smoking, etc)

It is not possible to remove all odours, but regular ventilation in addition to using air purifiers will help get rid of strong odours.