PM 2.5 face mask filters

I bought these PM 2.5 mask filters about a week back and they only arrived yesterday by post. I have a few reusable face-masks that require filters to be inserted. These were not too expensive and they look pretty well-made. But there will be some that will ask what use they are. After all, there are some reusable face-masks that do not come with filters. To answer these questions, this is what they are. A certified pm 2.5 filter  used with a fitted cloth mask can block the vast majority of airborne particulates, including up to 90% of fine aerosols. Thus, a pm 2.5 filter + mask is one of the most protective systems available. So go get some filters for your masks.