Video exposure monitoring as part of a strategy to assess exposure to nanoparticles.

OBJECTIVES There is a growing awareness of the potential risks for human health of exposure to ultrafine particles or nanoparticles. In that context, workplace air measurements become important, and various strategies have been developed to monitor exposure. In addition, observations and time/activity registrations are part of the exposure assessment strategy in many studies. Video exposure monitoring (VEM) can be of added value in these strategies. VEM combines exposure data with simultaneous video pictures of the process. METHODS The PIMEX method (Picture Mix Exposure) was used as the VEM studied. The possibility to combine PIMEX and measurement instruments for nanoparticles was the object of this study. The starting point was a review of available instruments for workplace air measurements of nanoparticles. Publications of strategies to assess exposure to nanoparticles were also studied to review whether observations were part of these strategies. Finally, a technical review of combining PIMEX and the compatible measurement instruments was undertaken and explored as part of the strategy to assess exposure to nanoparticles. RESULTS A variety of instruments are used to measure nanoparticles. One category is (near) real-time monitoring instruments, which determine numbers and particle size distribution or surface area concentration. Other instruments require sample collection in order to characterize the nanoparticles chemically and physically by microscopic analyses and/or elemental analyses. Only some of these instruments are technically compatible with PIMEX. With the PIMEX2008 version 1.02 software, it is possible to synchronize up to four different measuring instruments simultaneously with the video recording. CONCLUSIONS PIMEX as a VEM method can be a useful tool as part of the strategy to assess exposure to nanoparticles. It can also be of value for other purposes like training, education, and risk communication. The possibility to synchronize more than one measuring instrument can be useful to simultaneously monitor different targets in the workplace, e.g. worker exposure in the breathing zone and background concentration.