2.3.1. Cell Viability: Lactate Dehydrogenase (LDH) Assay

The cell viability of the bro-ALI models following exposure to clean air (sham) as well to air pollutants (DEP, gases and combined exposure) was assessed by measuring LDH release in BM collected 24 h after incubation of every exposure (e.g., exposure 1; exposure 2, exposure 3; Figure 1). The LDH measurement was analyzed using the Pierce™ LDH Cytotoxicity Assay Kit and performed in accordance with the manufacturer’s instructions (Thermo-scientific, MA, USA catalog no: 88953). In short, 50 µL of BM collected after the exposures were transferred to the 96 well-plates, followed by the addition of 50 µL reaction mixture to each sample well and then incubated for 30 min in dark, at room temperature. After the incubation, the LDH release was measured using a plate reader at 490 nm and 680 nm wavelength [24,30].