We collected samples from eight workers per day (Tuesdays, Wednesdays, and Thursdays), shifts ranging from 06.30 to 16.30. Sampling included personal air monitoring using two different air samplers, blood samples (for whole blood and plasma analysis), as well as spot urine samples. We washed all plastic materials used for sampling and analytical procedures in 10% HNO3 (v/v) and rinsed these materials four times with deionized water prior to use. When we used nitric acid in the study, we diluted it from 67%, Fisher Scientific, OPTIMA, UK.