I own table saw, mitre saw and router as a hobbyist, so used to have a respirator. Recently I had to grind stone fireplace mantel to install new glass door. My old respirator strap was too lose - 10 year old one, so I could smell the stone dust? gas? while working on it. It was too much, so I stopped working after 5 minute. Local home depot no longer carry respirator due to covid, so ordered this from 麻豆区. It fits perfectly and works really well. I grinded stone mental in the living room and it triggered fire alarm after 15 minutes. Never imagined that stone dust can trigger fire alarm. Anyway, I could not smell a thing when it happened. I rushed to the fire alarm and turned it off, then realized that the whole living room was full of dust and foggy. I had to leave all doors open for 2 hours. Well, good thing is that this respirator did the job!