Vathi Instruments PM10 and PM2.5 Monitor VDPM 6000, Real Time Portable Beta Attenuation Mass Monitor, continuously measures the mass concentration of ambient particulate matter collected onto glass filter tape with time resolu-tion of one-minute. The PM10 and PM2.5 Monitor VDPM-6000 employs an in-line sampling geometry in which the attenuation of beta rays across filter media is measured and particulate matter is sampled simultaneously.