Table 1—

Characteristics of study subjects

Subject	Sex	Age yrs	Smoking history	FEV₁ L	FEV₁ % pred	PC₂₀ mg·mL⁻¹
1	F	40	Non	2.41	66.5	0.26
2	M	20	Non	4.10	83.0	0.71
3	F	35	Non	2.58	80.5	0.18
4	F	55	Non	1.94	77.9	0.06
5	M	22	Ex^#	4.36	88.4	0.17
6	F	21	Non	2.82	77.6	0.37
7	M	53	Non	2.61	64.4	0.62
8	F	23	Non	2.29	60.5	0.05
9	M	48	Non	2.96	77.9	0.25
10	M	22	Non	6.00	112.2	0.09
11	F	21	Non	2.60	73.7	0.28
12	F	25	Non	2.83	74.4	0.03
13	M	40	Non	1.80	41.2	0.05
14	F	27	Non	2.55	65.6	0.06
15	M	21	Non	3.00	62.6	0.11
16	F	30	Non	3.50	106.1	0.67
17	F	30	Non	3.13	88.4	0.14
18	F	42	Non	2.41	67.4	0.07
19	F	20	Non	2.55	68.4	0.20
Mean		31.3		3.00	75.6	0.29

FEV₁: forced expiratory volume in one second
PC₂₀: provocative concentration of methacholine causing a 20% fall in FEV₁
% pred: percentage of the predicted value
F: female
M: male
Non: nonsmoker
Ex: exsmoker
^#: for 5 yrs