RESUMEN
Exposure to crystalline silica in the construction workers such as miners and diggers are widespread. Exposure to respirable silica [quartz] can results in silicosis. The goal of this study was to determine the contribution of each workers and component task to total dust and respirable quartz exposure in the tunnel of metro. The assessment of crystalline silica and total dust was performed according to standard procedure [NIOSH 7601]. Both total dust and quartz levels were high. The results of total dust in the digging process [37.63 +/- 0.76 mg/m[3]] were higher than in the cement work [9.88 +/- 0.80 mg/m[3]]. The maximum 8 h time-weight average concentration for quartz was found among the digging workers [0.407 +/- 0.006 mg/m[3]], followed by the barbed workers [0.11 +/- 0.008 mg/m[3]]. It can be concluded that the total dust contains high amounts of crystalline silica and it is responsible for the occupational exposure to quartz in construction workers. Thus, it is to be expected that the construction workers will suffer negative health effects due to exposure to the quartz dust