For each gravimetric analysis, the filters were weighed twice in a
preconditioned room (kept at a constant temperature and
humidity) before and after sampling were undertaken and the
personal dust exposure [8 h TWA (mg/m3)] calculated. The
weighed filter provides a mass of particles (in μg). The average
flour particles concentration obtained by the digital balance with
microgram accuracy (BIOS Sartorius, CPA224S, Germany).