Demographic characteristics at initial assessment
| Occupational asthma | Subjects with negative SIC | |
| Subjects n | 86 | 71 |
| Sex female | 33 (38) | 25 (35) |
| Age yr#,¶ | 35 (32–47) | 46 (34–54) |
| Education level† | ||
| ≤9 yrs | 22 (26) | 25 (36) |
| 10–12 yrs | 33 (38) | 33 (47) |
| >12 yrs | 31 (36) | 12 (17) |
| Unskilled labour§ | 31 (36) | 43 (61) |
| Smoking habitsƒ | ||
| Smokers | 8 (9) | 13 (18) |
| Exsmokers | 21 (24) | 25 (35) |
| Atopy | 52 (60) | 38 (53) |
| Referral by WCB | 51 (59) | 46 (64) |
| Agents suspected of causing symptoms n | ||
| Latex | 30 | 8 |
| Flour | 14 | 16 |
| Wood dust | 9 | 11 |
| Isocyanates | 7 | 11 |
| Metals, welding | 10 | 1 |
| Paints, resins, glues | 1 | 12 |
| Enzymes | 3 | 2 |
| Aldehydes | 1 | 4 |
| Antibiotics | 1 | 2 |
| Persulphate salts | 3 | 1 |
| Various chemical agents | 6 | 5 |
| Various animal or vegetal agents | 2 | 0 |
Data are presented as n (%) unless otherwise stated
SIC: specific inhalation challenge
WCB: Workers Compensation Board
#: median (25–75th percentiles)
¶: p=0.05
+: p=0.018
§: p=0.002
ƒ: p=0.038 comparing subjects with occupational asthma and those with negative S/C