Seasonal exposure to dust in flax processing in Egypt.

Previous evidence suggested that interruption of worker's exposure to flax dust may lead to severe symptoms of byssinosis on their return to work. In the present study, the prevalence and severity of byssinosis was studied in a sample of flax workers (n=577) who had been exposed to dust for six months each year. Byssinosis prevailed in 36.9% of them, and 32.3% of them had their FEV 1.0 sec reduced 10% at the end of the first morning work period (4 to 6 hours) of the week. Both syndromes were higher among seasonal workers than what would be predicted if they were pemanently exposed to flax dust. A hypothesis has been presented to interpret this finding.