The inhalable
dusts and metals were collected in an IOM sampler ((Milliporefilter,
25 mm AAWP, pore size 0.8 lm), and respirable crystalline
silica in an IOM foam sampler (Millipore-filter, 25 mm AAWP, pore
size 0.8 lm, foam (MultiDust Foam Discs for Respirable Sampling,
SKC Inc.)) at a calibrated flow rate of 2.0 L min1. After sample collection,
we gravimetrically analysed the filters of all IOM samples.