Table 1. Characteristics of the study population.

	Salmon workers (N = 139)	Trawler fishermen (N = 127)	P value*
Age, years
Mean (SD)	38.5 (11.7)	45.9 (9.9)	0.02
<35, n (%)	58 (41.7)	19 (15.0)	0.04
36–45, n (%)	41 (29.5)	33 (26.0)	0.03
46–55, n (%)	24 (17.3)	53 (41.7)	0.01
>56, n (%)	16 (11.5)	22 (17.3)	0.05
Smoking, n (%)			0.56
Current smokers	56 (40.3)	55 (43.3)	0.23
Former smokers	36 (25.9)	25 (19.7)	0.91
Never-smokers	47 (33.8)	47 (37.0)
BMI, mean (SD)	25.5 (4.1)	26.1 (4.1)	0.34
Education, years	12.0 (2.3)	12.9 (2.5)	0.72
Length of employment, years
Mean (range)	8.2 (1–33)	23.1 (1–47)	0.01
Asthma †, n (%)	10 (7.2)	5 (3.9)	0.13
In childhood,‡ n (% of asthma cases)	6 (60)	129	n/a
Allergy†, n (%)	14 (10.1)	15 (11.8)	0.48
Allergy to fish,‡ n (%)	6 (4.3)	8 (6.3)	0.10
Eczema,† n (%)	12 (8.6)	1 (0.79)	n/a
COPD,† n (%)	5 (3.6)	3 (2.4)	0.27

SD: standard deviation; BMI: body mass index; COPD: chronic obstructive pulmonary disease.

^*P value for Pearson Chi-square test (categorical variables), for independent-samples t-test (continuous variables).

^†Adult onset, self-reported doctor-diagnosed.

^‡Self-reported, n/a – not applicable (due to few cases among trawler workers).