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Fig. 1. Floor plan and distribution of TDI concentration in air samples of the velcro tape manufacturing factory. Big black dots indicate the place where samples were taken. ▨ indicates the place where the adhesive is applied to the tape; indicates the place where the adhesive is heated and dried.

found that the adhesive resin contained toluene diisocyanate (TDI), a well-known cause of occupational asthma [NIOSH, 1978; Chan-Yeung and Lam, 1986; NIOSH, 1977b]. Because TDI-induced occupational asthma has never, to our knowledge, been documented in Taiwan, this study was conducted to determine the etiology and prevalence rate of this outbreak of workers’ asthma.


The factory has 45 employees and has been in operation since 1984. Most of the employees were young women (median age 22 years). The female to male ratio was 3.2:1. The employees’ turnover rate was high; the average length of employment was 9.2 months. We tried to interview and examine all employees. Air samples were taken by midget impingers at different locations in the factory and they analyzed for TDI concentrations by colorimetric methods [NIOSH, 1977a]. Pulmonary function tests (PFTs) [Ferris, 1978] were also performed on workers, using a portable spirometer (Chest autospiror-298), during a usual workday, after a 10-day holiday, and 5 months after the improvement of the workplace by effective isolation and ventilation control. All tests were done in the morning (between 8:30–10:30 AM) at the factory office to avoid across-shift functional deterioration.

The factory was divided into three functional areas: the weaving area, where the tape is woven; the processing area, where the tape is dyed and the adhesive resin is applied; and the packaging/storage area. The three areas were connected through doors, with the packaging area in the middle of the other two (Fig. 1).

A case of asthma or asthmatic bronchitis was defined as any worker who

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