Measuring passive smoking: methods, problems, and perspectives.
The definition of passive smoking used by T. Hirayama [Brit. Med. J. 282, 183-185 (1981)] and other authors has at least three major shortcomings: it is only applicable to a highly selective sub-population; varying lifestyle patterns cannot be taken into account; and exposure outside the home is neglected. To overcome these shortcomings, a preliminary qualitative and classificatory definition of passive smoking that includes the total population as well as any smoke exposure, regardless of its location, was developed. This definition does not include the quantity of exposure or changes over time. Based on a representative survey, 17.8% of the population over 35 years are potential passive smokers according to this definition. The questionnaire developed by E.L. Wynder and associates (American Health Foundation, New York) presents difficulties in scoring the results for different lifestyles. Therefore a quantitative concept was developed for estimating exposure over any period of time as a generalized assessment instrument. The concept of maximum exposed M-time for an individual (TMI) as well as for a group (TMG) is introduced. The results are presented graphically by a cumulative standardized exposed M-time diagram. Results obtained so far lean toward plausibility and stability of the data and the concept. The interview form has still to be validated.