Table 1 Physical forms of cigarette smoke used in in vitro testing

Cigarette smoke condensate (CSC)

Comprises the particulate phase along with some vapour phase components. Generated by cold-trapping and condensation of smoke at extremely low temperatures. The condensed ‘tar’ is then typically extracted and diluted using acetone.

Cigarette smoke particulate matter (PM)

Comprises the particulate phase only. Particulates are typically collected by passing cigarette smoke through a Cambridge filter pad and are subsequently eluted from the filter pad using a solvent such as dimethylsulphoxide.

Cigarette smoke extract (CSE)

Comprises the particulate phase along with some vapour phase components. Generated by bubbling smoke through a liquid (e.g. phosphate-buffered saline or cell culture medium).

Whole mainstream cigarette smoke (WMCS)

Cells are directly exposed to smoke at the air-liquid interface. This is more representative of human exposure conditions, as cells are exposed to the gas and vapour phase components in an aerosol [5].