r/hazmat • u/PopularWedding52 • Jul 23 '25

General Discussion what is ppm mean?

Hey so i was exploring and found ppm clear on some of these rooms with dates next to them and others without them and a big x with caution tape on them. assuming its something important so id like to get more knowledge here

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u/AlarmedPossum156 Jul 23 '25

Without more information, I’m assuming that a room that has ‘PPM Clear’ on it means that all testing has chemicals or elements within acceptable ranges (aka a relatively safe area with limited or no PPE), whereas the other rooms with X’s had high levels of whatever they were testing/metering for.