That was non-expert opinion, maybe good masks have some sort of catalytic filter to trap very fine particles or gasses?
@4idan started
London Fixed Gear and Single-Speed is a community of predominantly fixed gear and single-speed cyclists in and around London, UK.
This site is supported almost exclusively by donations. Please consider donating a small amount regularly.
That was non-expert opinion, maybe good masks have some sort of catalytic filter to trap very fine particles or gasses?