An air–liquid interface system for toxicity studies of combined exposure to cigarette smoke and radon

While cigarette smoke (CS) is known to modify the risk of radon-induced lung cancer, the mechanisms remain poorly understood. Experimental studies on their combined effects are limited by the lack of suitable in vitro exposure platforms. This study provides proof-of-concept validation of a novel ALI exposure system for controlled, simultaneous exposure to radon and CS. The system comprises a 226Ra source, radon monitor, smoking machine, particle counter, siphon mixing unit, and an ALI system. The CS unit maintained the target concentration at 5 mg/m3 and induced dose-response toxicity in BEAS-2B cells following 0.5, 1 and 2 h exposures. For a 2-h radon exposure, the estimated average dose to the cells was 1 mGy (range 0.3–7.5 mGy), with a localized dose of 171 mGy per hit nucleus. Separate exposure to radon (2 h, 228 ± 54 kBq/m3) and CS (1 h, 5 mg/m3) resulted in 75 ± 9% and 83 ± 16% cell viability, respectively, while combined exposure led to a significantly lower cell viability (55 ± 8%). A trend toward an increase in pro-inflammatory IL-8 secretion was noted for all exposures; however, it did not reach statistical significance. The developed ALI-based exposure system enables precise dosimetry and biological assessment, establishing a validated proof-of-concept platform for future research on environmental co-exposures.