Carbon

O2 Nose Filters provide a more discreet form of protection against dirty air than the large masks

The Times

O2 Nose Filters are the latest weapon in the war against city pollution - air filters so small they can be worn inside a commuters nostrils.

London Post

'Invisible' air filter that you stick up your nose and blocks 90% of pollution particles, allergens and bacteria. It could help tackle the effects of the pollution crisis that plagues modern cities

The Daily Mail