It is widely recognized that machines used for standardized testing do not ‘smoke’ the same way people do. Different people smoke in different ways, and the same smoker may smoke differently at different times.
Still, most governments rely on the standard machine method for measuring tar, nicotine, and carbon monoxide levels in cigarette smoke. This method is approved by the International Organization for Standardization (ISO).
Machine testing allows measurements to be taken the same way anywhere in the world and enables uniform labelling of tar, nicotine, and carbon monoxide measurements on cigarette packages.
Under the ISO method, a cigarette is ‘smoked’ by a machine that takes a 35-millilitre (ml) puff of smoke, lasting two seconds, once per minute. This continues until the cigarette has been smoked to a point close to the filter tip. Tar levels are defined by the weight of the particulate matter collected on a filter pad in a laboratory when a cigarette is smoked by a machine after water and nicotine are subtracted.
A smoker may take more puffs, puff more strongly, or smoke more of the cigarette than the ISO-method machines, all of which would result in the smoker taking in more tar than indicated by standard testing.
For this reason, the Canadian government has developed a test whereby cigarettes are smoked on a machine far more intensely than in the standard ISO method. In Canada, emissions data printed on cigarette packages are displayed as a range between the lower ISO standard method numbers and the higher Canadian Intense Method results.
While this standard method provides a consistent way to rank tar, nicotine, carbon monoxide, and other smoke constituents, yields among different types of cigarettes, the machines do not measure the levels of smoke constituents an individual smoker would actually derive from cigarettes.