Table 1—

Definition of variables derived from information gathered at the first survey

Variables	Question answered at the first survey
Family and household factors
Mother has asthma	Does the child's natural mother suffer from asthma?
Father has asthma	Does the child's natural father suffer from asthma?
Older sibs	Does the child have older siblings?
Shares bedroom	How many other people sleep in the bedroom with the child?
Low SES	Lowest quartile of distribution of family socioeconomic status
Smoker at home	At least one person smoking in child's home
Smoking during pregnancy	Did the child's natural mother smoke during this pregnancy?
Environmental factors
Gas cooking	Is natural gas usually used for cooking?
Electric heating	Is your home heated by electric radiators or baseboard units?
Damp Spots	Have you ever had wet or damp spots on surfaces inside your present home?
Cat at home	Do you keep any of the following in the home: cats, dogs, rodents, birds?
Daycare	Did the child ever attend day care?
Mite allergy	Weal ≥3 mm with skin-prick test to either D. pteronyssinus or D. farinae
Exercise test
Exercise-induced bronchospasm	10% reduction in FEV₁ after a free run lasting for 6 min