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I've been using one of these:
I change the filters fortnightly.
The filter pictured is due to be changed this weekend.
Note the difference in colour of the edges (which aren't exposed to incoming air) and the centre of the filter (which is exposed to incoming air).
I'd rate this as between three and four times easier to breathe through than a surgical mask is.
Added bonus is that it frightens children, and some adults.
It also demonstrates quite well why Sadiq is trying to clean up the air in London.
Dyson headphones come with air vacuum for mouth