In the absence of other information, theatre-specific monitoring would be required to evaluate whether smoke/fog/haze machines are being used in accordance with the peak exposure guidelines.

ENVIRON developed Time-and-Distance (T&D) Guidelines as an alternative to conducting theater- and production-specific monitoring. These T&D Guidelines were developed under conservative use assumptions (e.g., no on-stage activities or props that would enhance dispersion, cue release at breathing height level). By following these T&D Guidelines, a production can use fog effects without having to conduct its own stage-specific testing, provided the machines are used in accordance with manufacturer specifications, are well maintained, and are functioning properly.

Find the guidelines here.