> 3M does not provide product information on which filters are best for government repression

That would be the 3M™ Organic Vapor/Acid Gas Cartridge/Filter 60923 [0]. Replace after each exposure or 30 days after opening the sealed packaging for best results. A clean shave is important for a good air seal.

The absolute best protection would be a PAPR (powered air-purifying respirator) with a TR-6530N filter [1] installed. Something like the 3M Versaflo M-407SG[2] would fit the filter and provide impact resistance. It can be fitted with a Speedglas 9100XXi [3] (or 9100X/V) auto-darkening filter for protection against flashbangs.

This is an equivalent PAPR [3] with a better form factor which also includes ANSI Z87.1 rated impact-protection (helpful against projectiles) and auto-darkening lenses (helpful against flashbangs/pyrotechnics). It also still works fine even if you keep a beard. I believe this is part of the Optrel Helix product line, which advertises 14-hour battery life. However, the listing I linked does not come with organic vapor / acid-gas filtration. That requires a different form factor for the filter, the Optrel ABE1P Combination Filter [4] offers A1B1E1P certification (Protects against organic gases/vapors, inorganic gases, acid gases, and particulates)

As 'closewith added, "CBRN" or "NBC" masks are also a good option - they are rated for chemical/biological/radiation/nuclear contamination and are available as riot gear with good impact-resistance. Look for A2B2E2K2-P3 ratings / certification.

You could also look into something like the Joseph Leslie Dynamiks A3B3E3K3-rated Jumbo canister for 10000 ppm extended exposure. [5]

0: https://www.3m.com/3M/en_US/p/dc/v000075263/

1: https://www.mcmaster.com/products/cartridges/manufacturer-mo...

2: https://multimedia.3m.com/mws/media/1892506O/3m-versaflo-m-4...

3: https://www.3m.com/3M/en_US/speedglas-welding-helmets-us/spe...

3: https://www.mcmaster.com/9258n17/

4: https://optrel.us/product/upgradekit-combifilter-swiss-air-5...

5: https://www.josephlesliedynamiks.com/brochures/Gas_Filters.p...

Best Gas Masks