One hundred and four carpenters who had been working with western red cedar woods over two years were examined by the use of the questionaire designed by the British Medical Research Council.
This investigation showed that there were ten patients with asthma (9.6% of the examined carpenters) and sixteen persons with persistent cough and/or phlegm (15.4% of them).
Two patients among the asthmatic subjects were known to have been attacked with the disease before beginning to work with western red cedar woods. However, one of the two was known to get asthma after beginning to work with lauans.
These ten asthmatic patients developed wheezing and dyspnea in the evening and night of working days.
Only one out of sixteen persons with persistent cough and/or phlegm was known to have had the symptom before beginning to work with western red cedar woods. This person had not worked with lauans.
On the subjects with the described respiratory symptoms, we examined respiratory functions, serum IgE, and skin reactions to extracts of western red cedar wood, house dust, candida, and broncasma berna. The results were compared with those of the controls who showed no respiratory symptoms in spite of the fact that they had worked with western red cedar woods. The following conclusions have been drawn :
1. As to the proportion of persons with increased IgE and that of those with positive allergy skin reactions against the four kinds of extracts, there are no significant difference between the asthmatic and the control group, because the former was being treated with steroid hormones. Among the persons with persistent cough and/or phlegm, subjects with increased IgE and those with positive allergy skin reactions to the extracts of the house dust are found more than among the control.
2. The asthmatic group has significantly higher respiratory resistance than the control. As to the other respiratory function tests (%VC, FEV1.0%, %RV), there are no significant difference between the former and the latter. The group of patients, with persistent cough and/or phlegm has higher respiratory resistance than the control, but the difference is not signifficant.
3. Among fourteen subjects who had persistent cough and/or phlegm and got the precise examination, eight persons have increased IgE (over 350 u/ml). These eight persons have less obstructive respiratory function disturbance than the other six persons without increased IgE.
It has been proved that persistent cough and/or phlegm develop more readily in subjects with increased IgE and skin sensitivity to allergen of the house dust.

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