The advantages and disadvantages of the various exposure measures used in industrial and nonindustrial settings are summarized in Table 6–1. The issues raised in this table are directly relevant to assessing ETS exposure. The use of surrogate measures derived from questionnaire responses and the issues resulting from use of these measures are discussed in this chapter.
Questionnaire responses of study subjects or family/household members are used for two purposes. First, questionnaires are used to obtain data on the physical characteristics of each environment and the time-activity patterns of the individual in each environment. These data can be used with individual monitoring data to estimate (usually by modeling) the air-contaminant levels in the microenvironment and to estimate time-weighted, integrated individual exposures. Second, questionnaire responses provide a basis for classification of individuals into broad categories of exposure based on self (or proxy) reports of exposure to individuals who smoke. Questionnaires of the latter type have provided the bases for associating ETS to the increased risk of nonmalignant and malignant disease.
There are several major issues in epidemiologic studies of health effects of exposure to ETS that rely on indirect measures of exposure as derived from questionnaire data.
First, the assessment of ETS exposures associated with acute health effects requires a different approach than that for chronic health effects. Acute health effects, such as respiratory infections, are manifested shortly after exposure and are of short duration. By inference, these health outcomes depend only on exposures in the recent past. In contrast, chronic health effects are conditions that are associated with long-term exposure to ETS, that is, they are manifested after some prolonged period of time and are of long duration. In evaluating the association of ETS with chronic diseases, knowledge about the duration of exposure and the duration of time from initial exposure to disease onset is more important than the duration of the disease.
Second, quality of information obtained by interview or self-administered questionnaires may vary among studies and may vary for different disease outcomes. For example, the assessment