Table 1.

Definitions of passive smoke exposure categories

Exposure category	Definition
Definitely exposed	All 3 of the following: At least 1 person smokes recorded within 2 years of RD No conflicting information from family members’ charts No mention in child’s chart that smoker smokes outside
Probably exposed	Conflicting information on smoking in household but at least 1 record stating there is a smoker in household or Meets criteria for “definitely exposed” and child’s record mentions that all smokers smoke outside or Meets criteria for “definitely exposed” and only available information is recorded > 2 years before RD
Probably not exposed	One parent is nonsmoker. No smoking information on other parent or Child’s record states household is nonsmoking and 1 or more adults quit smoking within the last 5 years or quit at an unknown date or Any family member’s record states that no one in household smokes or Both parents documented as nonsmokers or former smokers but information on at least one parent is > 2 years before RD
Definitely not exposed	Unequivocal information from child’s record within 2 years before RD that no one in household smokes or Information within 2 years before RD that both parents are nonsmokers. Any former-smoker parents quit more than 5 years before RD.
Unknown	No smoking-related information found in subject’s or any family member’s medical record

RD = reference date (date of culture collection).