Table 5.

Demographics of June 2002 participants by respiratory symptom status.

	Respiratory case group (n = 140)	Fewer symptoms group (n = 63)	Comparison group (n = 44)
Female (%)**	73	44	59
Age [years (mean ± SD)]	47 ± 8	46 ± 9	46 ± 8
Occupancy duration [years (mean ± SD)]	7 ± 2	7 ± 2	7 ± 2
Current smoker (%)	17	6	9
Never smoker (%)	56	70	70

Due to missing values, age and duration of occupancy in respiratory case group are based on 137 participants. For age, n = 62 in the fewer symptoms group and n = 42 in the comparison group.

^**p = 0.0004 by Chi-square test on sex.