All workers exposed to wood
dust at their work sites (sawing, cutting, debarking and
planing of wood, and parquetry production) were invited to
participate. Recruitment was on a voluntary basis after an
invitation issued by their employers. All participants signed
informed consent and were free to leave the study at any
time. A total number of 96 wood-processing workers were
examined, 35 from SM 1 and 61 from SM 2. Response rates
were 98% for SM 1, and 84% for SM 2. An inclusion criterion
for participating in the study was exposure to wood dust for
≥ 20 hours per week, and absence of contraindications for
skin prick test. Most of the workers did not wear personal
airway protection. The main characteristics of the study
subjects (gender, age, duration of work exposure in the woodprocessing woodprocessing
industry, smoking habit) are presented in Table 3.
Study protocol for the subjects included a medical interview
according to a modified organic dust questionnaire, physical
examination, and skin prick testing.
A questionnaire based on the ‘Organic Dust Questionnaire’
was completed by the physician who interviewed each
subject [16]. Smoking habit was expressed as a dichotomous
variable (smokers and non-smokers) and as a smoking index
(number of cigarettes smoked per day х number of smoking
years). Only current smokers were designated as smokers.
The questionnaire recorded reports on the occurrence of
work-related eye, respiratory, skin and general symptoms
during the last 12 months. In this study, only upper and
lower respiratory airway symptoms were analyzed. Upper
respiratory symptoms included sneezing, rhinorrhea,
nasal itching and nasal obstruction (not related to the
common cold). The variable ‘rhinitis’ was defined with 2 or
more upper respiratory symptoms being recorded. Lower
respiratory symptoms included dry cough, phlegm (cough
with expectoration), wheezing and dyspnea. The variable
‘asthma’ was defined as the recording of wheezing and/or
dyspnea. Chronic bronchitis was defined as persistent cough
and phlegm for more than 3 months per year, lasting for
more than 2 years. Contraindications for skin prick test
were evaluated for each subject during completion of the
questionnaire and physical examination.