Table 1—

General and respiratory health characteristics of the study population (random sample) by occupational group

OfficeCleaningHigh MWLow MW
Total44923043241181
Females3008 (67.0)254 (83.6)164 (50.6)180 (15.2)
Age ≥35 yrs2152 (47.9)155 (51.0)125 (38.6)502 (42.5)
Current smokers1451 (32.3)151 (49.7)152 (46.9)536 (45.4)
Current asthma#308 (6.9)43 (14.1)35 (10.8)94 (8.0)
Chronic bronchitis107 (2.4)20 (6.6)25 (7.7)60 (5.1)
Bronchial hyperresponsiveness+449 (13.7)42 (24.3)35 (15.0)107 (11.9)
COPD§61 (1.6)8 (3.6)11 (4.0)27 (2.7)
Atopyƒ1097 (33.3)55 (26.7)81 (32.8)314 (34.5)
  • Data are presented as n (%) unless otherwise stated

  • MW: molecular weight

  • COPD: chronic obstructive pulmonary disease

  • #: attack of asthma in the past 12 months, and/or woken by an attack of shortness of breath in the last 12 months, and/or current use of asthma medication

  • : productive cough on most days for at least 3 months each year. Missing data for 11 subjects

  • +: a fall of at least 20% in forced expiratory volume in one second (FEV1) associated with a methacholine dose of ≤1 mg, n=3283, 173, 233, and 897, respectively

  • §: FEV1 <80% pred and FEV1/forced vital capacity ratio <0.7, n=3729, 224, 274, and 1003, respectively

  • ƒ: specific immunoglobulin E to common allergens, n=3292, 206, 247, and 910, respectively