A schematic representation of the major components of the Vitrocell® VC 10 smoke exposure system. [a] Computer, software controller and air-flow controller, which determines the smoking parameters and key machine settings. [b] Smoking Robot carousel where cigarettes are loaded and smoked, enclosed within an extraction ventilation hood. [c] Piston/syringe which draws and delivers an ISO or Health Canada Intense puff (35 ml or 55 ml) of mainstream cigarette smoke to the smoke dilution system. In our set-up smoke is exhausted to the dilution system over 8 seconds, however this can be adjusted. [d] Dilution, transit and delivery of whole smoke occurs in the dilution bar, of which multiple bars can make up the complete dilution system. Continuous diluting air is added perpendicular to the mainstream smoke in the range 0.2-12 L/min and administered to the dilution bar through smoke air jets of 2.0 mm diameter. Airflow rates are set by mass flow meters, which can be upgraded to mass-flow controllers. Flow within the dilution system is continuously transiting through to exhaust. [e] Smoke exposure module (Vitrocell® 6/4 CF Stainless Steel module or Vitrocell®-AMES) which holds the Transwells® or agar plates which are maintained at the ALI or AAI. Smoke is sampled from the dilution system into the exposure module via negative pressure applied through a vacuum pump at 5 ml/min/well. Smoke is distributed within the exposure module via the smoke ‘trumpet’ inlets and, due to the linear configuration, each culture insert is isolated receiving an independent sample of smoke from the dilution system. The central islands can be removed and quartz crystal microbalances can be installed into each position or, as shown here, in position 4.