Hanging drop: An in vitro air toxic exposure model using human lung cells in 2D and 3D structures

► Validated for the first time a hanging drop (HD) air toxic exposure method for inhalation exposures effect studies. ► Applied a four compartment mass balance model to calculate cellular exposure levels. ► Compared A549 2-dimentional (2D) cell culture and 3D cell cultures benzene sensitivity. ► Carried out up to 20 days in vitro exposure studies. ► Validated A549 cell hanging drop toluene and xylene exposure EC50 value with published static apical air exposure method.