Although a machine brings standardisation it does not reflect how people smoke
It is widely recognised that machines do not ‘smoke’ the same way as people do. Not only this, but people smoke differently from each other, and the same smoker may smoke differently in different circumstances.
However, most governments still rely on the standard machine method for measuring the tar, nicotine and carbon monoxide levels in cigarette smoke, which is approved by the International Organization for Standardization (ISO).
This allows the measurements to be done the same way anywhere and enables uniform labelling of tar, nicotine and carbon monoxide measurements on cigarette packs, expressed in milligrams (mg) per cigarette.
The ISO standard method
Using the ISO method, a cigarette is ‘smoked’ by a machine, which takes a 35 millilitres (ml) puff of smoke lasting two seconds, once per minute. This continues until the cigarette has been smoked down to a point close to the filter tip. Tar levels are measured by extracting water and nicotine from the particulate matter collected on a filter pad.
While this standard method gives a consistent way of ranking tar, nicotine and carbon monoxide yields among different types of cigarettes, the machines do not measure what tar yield levels individual smokers actually get from cigarettes.
A person may take more puffs, puff more strongly or smoke more of the cigarette than the smoking machines using the standard ISO method, all of which would result in the smoker taking more tar than indicated by the standard ISO method.
This means the tar level shown on a cigarette packet does not indicate the actual amount an individual smoker gets. So, for example, someone smoking a cigarette labelled ‘5 mg tar’ cannot assume they are getting 5 mg of tar (they may take much more), and they should not assume they will take half the tar of a cigarette labelled ’10 mg tar’.
Public health community views
The World Health Organisation (WHO), the US National Cancer Institute and others in the public health community have also raised concerns about the fact that cigarette deliveries are not accurate measures of smokers’ exposures or health risks.
Some public health reports suggest that, when switching from cigarettes measured as higher tar and nicotine yields by the current ISO machine method to products measured by that ISO method as lower tar and nicotine yields, smokers might change their smoking behaviour to take as much tar and nicotine as they would from cigarettes measured as higher tar.
The WHO is investigating whether there are better ways of measuring actual yields. We believe this is important and we are undertaking research aimed at contributing towards improving measurement standards.
Our scientists are working on filter analysis as a way towards understanding how much smoke and yield levels people actually take in day-to-day human smoking conditions.
Estimating yields of different types of cigarettes to allow for human smoking behaviour involves measuring the tar and nicotine in the butts of cigarettes which have been smoked by people. This gives us an estimation of the amount of smoke constituents which actual smokers draw through the filter.
We are carrying out this type of research in several countries and our scientists have presented the methodology for our filter analysis study to the European Conference of the Society for Research on Nicotine and Tobacco , an academic organisation whose members include many of the leading researchers in the field of nicotine and tobacco science.
Our research continues to be written up and our aim is to see it published in peer-reviewed journals. For more information on our papers and presentations, see our science website .