Airborne levels of total and respirable dust, quartz, polycyclic aromatic hydrocarbons, and elemental carbon in an ascon manufacturing environment were assessed to determine operators’ exposure and the likelihood of developing occupational respiratory diseases.
The ascon production process is divided into four steps, namely feeding, drying, mixing and loading. The feeding process is to transfer aggregate to conveyors underground via. The drying process is intended to remove moisture from the aggregate and maintain the temperature required for mixing the aggregate, asphalt and additives.The mixing process blend with the aggregate, asphalt and additives to make ascon. The loading process involves loading dump trucks with ascon, which is disgorged from an outlet on the mixing machine.
The airborne levels of total and respirable dust and quartz at hopper 1 were 8.540, 1.536, 0.125 mg m-3 . The airborne levels of total and respirable dust and quartz at hopper 6 were 10.092, 3.989, and 0.331 mg m-3 . At the vibrating screen, the airborne levels of espirable dust and quartz were 12.362 and 1.645 mg m-3 . The level of airborne elemental carbon from a burner of a dryer was 0.001 mg m-3 . The levels of total and respirable dust and quartz at the mixer outlet were 0.685, 0.265, and 0.011 mg m-3 . The levels of total and respirable dust and quartz in the dump truck zone were 0.419, 0.036, and 0.011 mg m-3. Only naphthalene was much lower than 10 ppm PEL of naphthalene. The naphthalene levels measured in the dryer burner, dump truck zone, dump truck waiting zone, and operation room were 0.274, 0.138, 0.192, and 0.237 ppm. The naphthalene levels measured in the conveyors on the ground, vibratory sieve, bunker C oil tank, and mixer outlet which were 0.074, 0.088, 0.080, and 20.074 ppm were generally very low. During the operation tasks, the personal exposure levels of total and respirable dust were relatively low, at 0.027 and 0.013 mg m -3 . Respirable dust and quartz levels of the operator were 4.260 and 0.548 mg m-3 when cleaning the conveyors underground.
Based on this study, we can conclude that concentrations of PAHs are hardly emitted at the ascon mixing plant, during ascon production. On the contrary, the aggregate dust highly containing quartz is significantly released during ascon production. In terms of ascon manufacturing environment anagement, this study means an environmental evaluation is the first time for those substances developed with lung cancer at ascon manufacturing site.