> everyone should just have a full face gas mask for all hacker-ish activities, like painting

Not everyone who wears eyeglasses, unless you're prepared to add another several hundred dollars for the lens holder and set of prescription lenses.

I do have the 3M 6800 full face respirator but almost never use it. The silicone 7xxx series is much more comfortable than the rubber 6xxx series, and the 750x silicone half mask is reasonably priced. Augment with comfortable googles as necessary (vented ones work for me since I'm painting, not rioting).

For the UK/EU types, GVS make a good half resporator mask:

https://www.gvs.com/en/catalog/elipse-p3-respirator

This one is good for standard DIY duties that do not involve chemicals (ie cutting, grinding, sanding)

there is a quite readable guide you can get here: https://www.hse.gov.uk/pubns/priced/hsg53.pdf

For chemical resistance: https://www.gvs.com/en/catalog/elipse-a1p3-respirator

BUT you need to worry about mucus membranes (ie eyeballs can absorb some chemical). The A1 bit means that it'll protect against PPM that are less than 1000, (No I don't know what the PPM of teargas is.)

I guess but cannot assert that decent hardened safety goggles will help against gas in the eyes, but again you'll need to look at the standards for that. the all in one mask/face shields are a better bet.

Your local hardware store should carry this kind of stuff, especially if they do any kind of plastic solvent or fibreglass/epoxy stuff.

If you are the kind of person who has forgone wearing a mask or eye protection while working on a project because you thought you could be done quickly or it was too much of a hassle or too uncomfortable for the "little" amount of benefit it would have: get a full-face mask.

Full-face masks are so much more comfortable, so much clearer to see through than those stupid yellow sunglasses that get scratched up all the time, so much easier to put everything on, so much better in every aspect that you won't think twice about it anymore. You walk into the shop, grab the one thing, put it on, and get to work.