Tar and nicotine ratings on cigarette packets are not worth the paper they're written on

Professor Martin Jarvis, Imperial Cancer Research Fund

The levels indicated on packaging are based on machine measurements.

The problem is that these readings take no account of the different ways that smokers actually puff on cigarettes.

Professor Jarvis said: "Nicotine and tar yields printed on packets are measured by machine but people don't smoke cigarettes like a machine.

"Smokers need to satisfy their craving for nicotine so change the way they smoke to ensure they get the hit they need, whatever the nicotine or tar rating of their particular brand."

Professor Jarvis said the study found little evidence that smoking lower nicotine brands resulted in less exposure to nicotine and tar than smoking normal cigarettes.

Nicotine analysis

Professor Jarvis' team analysed levels of a by-product of nicotine called cotinine in the saliva of 2,031 adult smokers.

They found that smokers of very low nicotine cigarettes inhaled about eight times more nicotine than stated on the packet, whereas smokers of higher nicotine brands took in about one-and-a-half times as much.

"Ultra low tar" brands claiming to deliver just 0.1 milligram (mg) of nicotine, actually delivered closer to 1 mg.

Professor Jarvis said: "Lower nicotine brands use special filters with vents which, when smoked on a machine, greatly dilute the smoke with air and reduce the measured level of nicotine and tar.

"But we found that smokers can take in essentially whatever amount of nicotine (and therefore tar) they need by sucking harder, longer and more frequently, and by blocking ventilation holes with their lips or fingers.

"The conclusion has to be that the tar and nicotine ratings on cigarette packets are not worth the paper they're written on."

Other findings of the study include:

• Overall, the smokers in the study preferred higher nicotine-yielding brands, probably because getting the desired amount of nicotine from the "light" brands requires a fair amount of effort
• Smokers of low nicotine brands tended to be older, female and better educated
• The amount of nicotine taken in by smokers varied widely, irrespective of whether they were smoking a high or low nicotine brand