A method for monitoring occupants (108, 112) of a vehicle comprising: obtaining successive images of an interior cabin of the vehicle from an occupant facing camera; identifying a respective body region for one or more occupants of said vehicle within an obtained image; identifying within at least one of said body regions, a plurality of skeletal points including one or more points on an arm of a body; identifying one or more face regions within said obtained image; identifying one or more hand regions within said obtained image; determining a hand region to be either a left (312-L) or a right hand (312-R) of an occupant in accordance with its spatial relationship with identified skeletal points of said body region of said occupant; determining a face region to be a face region of an occupant in accordance with its spatial relationship with said body region of said occupant; analysing a spatial relationship of a determined left or right hand region and a determined face region to determine a provisional state of said occupant; providing at least said determined left or right hand region for said occupant to a classifier (316,318) to provide an activity classification for said occupant; combining said provisional state of said occupant and said activity classification, the method further comprising: monitoring an identified face region through successively obtained images to make a provisional classification that said occupant is smoking, said monitoring comprising: monitoring a contrast level of said identified face region through successively obtained images; and analysing changes in said contrast level over time to make said provisional classification that said occupant is smoking; and combining said provisional classification that said occupant is smoking with said provisional state of said occupant and said activity classification to provide a final state for said occupant. obtaining successive images of an interior cabin of the vehicle from an occupant facing camera; identifying a respective body region for one or more occupants of said vehicle within an obtained image; identifying within at least one of said body regions, a plurality of skeletal points including one or more points on an arm of a body; identifying one or more face regions within said obtained image; identifying one or more hand regions within said obtained image; determining a hand region to be either a left (312-L) or a right hand (312-R) of an occupant in accordance with its spatial relationship with identified skeletal points of said body region of said occupant; determining a face region to be a face region of an occupant in accordance with its spatial relationship with said body region of said occupant; analysing a spatial relationship of a determined left or right hand region and a determined face region to determine a provisional state of said occupant; providing at least said determined left or right hand region for said occupant to a classifier (316,318) to provide an activity classification for said occupant; combining said provisional state of said occupant and said activity classification, the method further comprising: monitoring an identified face region through successively obtained images to make a provisional classification that said occupant is smoking, said monitoring comprising: monitoring a contrast level of said identified face region through successively obtained images; and analysing changes in said contrast level over time to make said provisional classification that said occupant is smoking; and combining said provisional classification that said occupant is smoking with said provisional state of said occupant and said activity classification to provide a final state for said occupant. monitoring an identified face region through successively obtained images to make a provisional classification that said occupant is smoking, said monitoring comprising: monitoring a contrast level of said identified face region through successively obtained images; and analysing changes in said contrast level over time to make said provisional classification that said occupant is smoking; and combining said provisional classification that said occupant is smoking with said provisional state of said occupant and said activity classification to provide a final state for said occupant.