I wrote this before I realized this was an old thread...but posted it anyway as consumer grade dust masks are garbage.
You say that "I still feel like I'm inhaling dust even when wearing a dust mask." If you have dirty boogers after wearing a dust mask, then the dust mask is not doing it's job. Most likely the mask does not fit your face well and air is leaking past the mask at the bridge of your nose.
While I get stuffy while wearing a dust mask - I think due to the high humidity and general sinus issues - I don't get dirty boogers while wearing a mask. I work in industrial settings that are extremely dirty and try to take good care of my lungs (and eyes and ears and fingers).
For home use in the woodworking shop, I use Lee Valley's "Comfort-fit Respirator". This is a silicone rubber mask with replaceable N95 paper filter elements. Things I like are 1) the rubber mask seals to my face well, 2) the strap system allows the mask to hang around my neck when I don't want it on my face, 3) it is light, not bulky and I can manage to wear safety glasses and hearing protection (muffs) all at the same time. Unfortunately with this type of mask you cannot test the mask-to-face seal. I replace the paper element in this mask about once a year.
Most consumer grade paper masks are garbage. If you want to use a paper mask, get a real mask that has a metal/foam adjustment at the nose-bridge, get an exhalation valve to help prevent safety glass fogging, and get a mask that has a N95 or higher rating. Masks that don't mention their filtration efficiency should be avoided. I like the Moldex 2700 N95 mask with handy-strap. I keep one of these stashed in my hard-hat for when unexpected dust events happen. They cost $5 each, but at home one of these masks will last for months. Surprisingly the same model with N100 rating doesn't fit my face well and always leaks at the bridge of my nose, so I use the N95 mask.
I personally don't worry too much about filtration efficiency of N95 vs. N100 (or P100 which also protects against hydrocarbon aerosols). It is more important to insure a good mask-to-face seal.
For power sanding at home I connect the sander to a shop vac with HEPA exhaust filter and I wear a dust mask.
Basically if you get a comfortable mask that works well, you will wear it most of the time. A cheap mask that is uncomfortable and doesn't filter well will sit on the shelf collecting dust.
For work I use MSA Comfo-Elite half-mask respirators (with organic cartridges and separate dust prefilters). The silicone half-mask conforms to my face and provides a good seal. You can easily test the seal by placing the palms of your hands over the cartridges and breathing in; if the mask sucks to your face you have a good seal. Sometimes I use the 3M 6800 full face respirator with 2091 P100 dust filters. This is a comfortable mask that is more balanced than a half mask. It also keep dust out of your eyes. It has lower profile than the half-mask allowing you to crawl through smaller spaces where the half-mask cartridges tend to catch on protrusions and rip the mask off your face.
Now I have to post two photos. I sometimes work in a Chinese coal mine, in the processing plant. Personal protective equipment in China is a sign of status; only wealthy foreigners get PPE. Welders and labourers work in dusty environments that completely plug off my dust mask within 2 hours (I have to leave the job-site to get to a clean area to take my mask off and replace the plugged cartridges). This is me:
I saw one of the welders walking past me at work....he actually had a respirator hanging around his neck...obviously unused because his face is black with dust. His lungs are just as full of dust. Sad that he probably doesn't have the education to understand the danger; or perhaps his boss refuses to buy replacement filter cartridges so once his cartridges are plugged he has to breath dust.
That's dust on his face!
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