Cigarette companies measure average per cigarette yields of tar, nicotine, and carbon monoxide using standardized machine test methods. Regulations in most countries require that the companies use the test method developed by the International Organization for Standardization (ISO). In the U.S., companies follow the method that was developed in 1967 in cooperation with the Federal Trade Commission (FTC). Another well-known machine test method was developed by Health Canada, the regulatory agency regulating tobacco products in Canada. These methods compare the tar, nicotine, and carbon monoxide yields of different brands of cigarettes when smoked by a machine under identical laboratory conditions, and indicate their relative differences in yields.
Machine test methods compare different cigarette brands when “smoked” by a machine under identical laboratory conditions. As regulators have said since their introduction, these tests show the relative differences in yields among brands, assuming that each brand is held and smoked the same way as it is in the machine. For example, in the ISO and FTC methods, the machine takes one two-second puff of a specific volume of smoke (35 milliliters) every minute. In the Health Canada test method, ventilation holes in the cigarette filter are blocked, and larger and more frequent puffs (55 milliliters once every 30 seconds) are taken. As a result, the tar and nicotine yields of the same cigarette brand are much higher when the Health Canada method is used. The Health Canada method is often referred to as the Health Canada ‘intensive method.’
In 1967, the FTC stated, “No test can precisely duplicate conditions of actual human smoking and, within fairly wide limits, no one method can be said to be either ‘right’ or ‘wrong’—the purpose of testing is not to determine the amount of tar and nicotine inhaled by any human smoker, but rather to determine the amount of tar and nicotine generated when a cigarette is smoked by machine in accordance with the prescribed method.”
A number of public health organizations, including the World Health Organization (WHO), have stated that the ISO and FTC methods provide misleading information about tar and nicotine inhaled by a smoker, and recommended that tar, nicotine, and carbon monoxide numbers should not be disclosed to consumers. However, many countries require those numbers to be printed on packs of cigarettes and, in some countries, in advertisements.
WHO’s Study Group on Tobacco Regulation and the Conference of the Parties’ Working Group on tobacco regulation have recommended using both the ISO and the Health Canada method for cigarette smoke constituent testing.
No two smokers smoke cigarettes exactly the same way. The tar and nicotine yield numbers that are reported for cigarette brands are not meant (and were never intended) to communicate the precise amount of tar or nicotine inhaled by any individual smoker from any particular cigarette. Yield numbers, however, allow smokers to compare brands based on different taste characteristics.
Smokers should not assume that the numbers printed on packs or in advertisements indicate with precision the actual amount of tar, nicotine, carbon monoxide or any other smoke constituent that they will inhale from any particular cigarette. And smokers should not assume that lower numbers mean that a particular cigarette brand is safe, safer or less harmful.