@baz10 My docs and the NIH say to use a specific type of mask called N-95 to protect against small particles.This is actually a disposable respirator with a filter device in the center that the air flows through, and in my opinion it is not so easy to breather through, but it is far more effective than the type you see everywhere. It needs to be fitted carefully to your face, and replaced after 6-8 hours of use or if it gets wet or torn. These are widely available on-line, and through big-box home improvement stores, and sometimes at Walgreens. I get them at the local big-box store in a pack of 10 for $20, which lasts my husband and me all season and we both wear them.

There are also surgical type masks made by 3M than are 99% effective at filtration of very small particles of 0.1 microns. That's as good as HEPA filtration in the paper filter material. They have ear loops and are latex free. This wouldn't fit as tight as a respirator or a dust mask in sealing out stuff, but they are comfortable and do a pretty good job. I have asthma and find that these reduce exposure and help my allergies. You can buy them online. I sometimes wear 2 at the same time for extra protection and sleep with them on too. I keep them in my car for when I drive past smoke or dust and I can put them on quickly. They are 3M #1820 disposable Procedure Masks and come in boxes of 50.