Table 1 Selected characteristics of participants with no history of physician-diagnosed asthma at study entry

Selected characteristics at study entry*	N (2057)	Ratio of observed to total possible person-years†
Age at entry (years)
7–9	1441	0.80
10	557	0.79
11–12	59	0.67
Race/ethnicity
Non-Hispanic white	1094	0.80
Hispanic	651	0.79
African-American	110	0.70
Asian	101	0.86
Mixed	63	0.76
Other/unknown	38	0.60
Gender
Female	1095	0.80
Male	962	0.78
Overweight at entry
No	1778	0.79
Yes	279	0.77
Parental history of asthma
No	1651	0.80
Yes	273	0.79
History of allergic rhinitis
No	1688	0.79
Yes	322	0.78
Humidifier use
No	1470	0.80
Yes	497	0.77
Maternal smoking during pregnancy
No	1700	0.80
Yes	293	0.74
Postnatal maternal smoking
No	1830	0.80
Yes	189	0.74
Household second hand smoking
No	1658	0.80
Yes	357	0.76
Pests in home
No	1455	0.76
Yes	923	0.80
Dogs in home
No	923	0.79
Yes	1134	0.79
Pets in home
No	495	0.79
Yes	1562	0.79
Health insurance
No	358	0.78
Yes	1661	0.79
Parental income (US$/year)
⩽14 999	307	0.74
15 000–49 999	749	0.79
>50 000	697	0.81
Parental education
Less than high school	295	0.77
At least high school	392	0.79
Some college	822	0.79
College and above	464	0.81
Cohort
1993	1046	0.80
1996	1011	0.78