Copy and pasting this because I don't want to have to type it out again.

As some topical words of advice, most respirators are not meant for use in IDLH atmospheres. IDLH means Immediately Dangerous to Life or Health. It means if your mask fails, or you take it off, the atmosphere will prevent you from escaping, kill you, or severely injure you. Since that's usually what people are thinking of when they say they're looking for a gas mask or respirator... you need to be careful about what you're buying. Don't buy a "respirator" when you really want a "gas mask".

There's also more to appropriate use of gas masks and respirators than just buying them and putting them on when the time comes. You need to understand that respirators do not universally stop all contaminants at all concentrations. Most do nothing for you in fires where carbon monoxide is present, nor do they do anything in oxygen-deficient atmospheres. If the concentration of a contaminant is too high, it may also "break through" the filter. So it's generally not a good idea to leave a "safe" location for, or to travel through, an unknown one. And finally, don't think evacuation orders don't apply to you or give you more time because you have PPE.

Check into Avon's masks. https://www.avon-protection.com/ If you're serious, do it right or don't do it at all.