ATP viability test on A549 cells exposed to cobalt. The cells were cultured for 24 h with increasing concentrations of cobalt. Cell viability was determined by ATP Celltiter-Glow Luminescence Cell Viability Assay (Promega). Measurements were made on the Lumistar Galaxy (BMG) luminometer. The viability (V) was determined as the ATP ratio of treated cells versus control cells in %. The results are presented as mean ± SD (n = 4 to 8).