Smoking in vehicles is lower than mobile telephone use while driving, but is socially patterned.

Legislation is being considered which bans smoking in cars carrying children under the age of 16. This was an observational survey of smoking by drivers and passengers and mobile phone use by drivers in 2,230 cars over three time periods in two Dublin locations. The observed prevalence of mobile telephone use (2.56%) was higher than smoking (1.39%) (p < 0.01), but was low in both. There was no significant variation according to time of day. There was an inverse pattern according to car value for smoking drivers (p = 0.029). Eight adult passengers and just one child were observed as being exposed to a smoking adult driver. In conclusion, the public health importance of regulating passive smoke exposure is clear but the resources required to police such a ban in vehicles may be labour intensive for the yield in detection or prevention.