Things have changed a whole lot since you first posted asking about masks. In my state, they are currently required to enter almost every public building, open business (most are still closed), medical facility, etc.

If you still have questions about them, what type, what material, etc, the Pennsylvania Department of Health website has reliable info. I use their specs to make masks (yes, I sell them, no, this is not sales pitch as I already have more orders than I can fill).

As for your 3M painter's mask: if the air is just going around the mask, you're not wearing it correctly. There should be a flexible piece at the top that needs to be bent down tightly over the nose to create a seal and the elastic needs to be tight around your head/ears (depends on the style). Also, if you have facial hair that may prevent the masks from creating an effective seal.