PSE increases children’s risk of pneumonia, bronchitis, respiratory illness, wheezing, middle ear effusions, and otitis media (Etzel, 1994; National Research Council, 1986; USDHHS, 1986; U.S. Environmental Protection Agency, 1992), and risk of complication increases with higher levels of exposure (DiFranza sellckchem & Lew, 1996). A number of biological mechanisms that interfere with lung function and growth (Cook & Strachan, 1999) and immune responsiveness (USDHHS, 2006) have been postulated to explain how PSE causes injury and disease. Children with cancer may be especially vulnerable to these insults secondary to disease and treatment-related toxicities that may affect their pulmonary, respiratory, and cardiovascular functioning (Benoist et al., 1982; Lipshultz et al., 1991; O’Driscoll et al., 1990).

In addition to greater risk for later cardiovascular or pulmonary disease (USDHHS, 1995), continued PSE may exacerbate pediatric cancer patients�� risk for developing second malignancies (Meisler, 1993; Neglia et al., 1991; Robison & Mertens, 1993). Interventions designed to protect children from PSE are dependent on reliable measures of PSE. It is critical to know the social context in which PSE takes place and the time course or episodicity of both acute and chronic exposure. Such details are obtained only by observation in public settings or by report of persons routinely in such settings, such as parents in their private home. A number of behavioral, environmental, and biochemical measures have been used to quantify the magnitude of children’s PSE in their homes and cars (Matt, Bernert, & Hovell, 2008).

Parent reports are the most common method of assessing smoking behavior and exposure rates in the social and physical contexts of the young child (Hovell, Zakarian, Wahlgren, Matt, & Emmons, 2000). Parent reports are noninvasive, relatively inexpensive, and can be repeated over time. However, as is true of all measures, reports can be compromised by memory, distractions, or bias, where risk of penalty might lead parents to underestimate (or overestimate) level of PSE. Thus, it is important to assess the reliability and accuracy of reported measures to set the stage for clinical research and service programs aimed at reducing child PSE (Matt et al., 2000). Past studies have demonstrated that smoking mothers can provide reliable and valid reports of sources and patterns of their child’s PSE (Emerson et al., 1995; Emmons et al., 1992; Emmons, Hammond, & Abrams, 1994; Matt et al., 1999, 2000), with 20%�C40% of the variance in biomarkers of exposure accounted for by quantitative parent reports of exposure. For example, Matt et al. (2000) reported Brefeldin_A correlations of .62 and .