Yesterday Robert and I found that the pump in the mechanical room that pulls air for the dust monitors that have their internal pump removed was not pulling air. Today I read the flow on the attached flow meter as .15. This means that the data from locations 1 (ISCT4), 7 (H2 racks) and 10 (H1 PSL) has been invalid for an unknown period of time. Also possibly location 8 (H1 racks), which had been replaced with one with an internal pump earlier. So today I went and replaced locations 1, 7 and 10 with ones that have an internal pump. Note also that dust monitor 3 was moved yesterday into a clean room next to where the jack hammering is taking place. Also for a period yesterday, location 4 was moved onto the floor by the H1 PSL, but has been moved to location 8 today. Locations of LVEA dust monitors: 1 ISCT4 3 Clean Room over BSC4 5 Beer garden 6 Diode room 7 previous location of H2 racks 8 H1 racks 10 H1 PSL