the primary measurements of
xylene vapors found a mean concentration of
4.7¡5.5 ppm (ranging from 0.3 to 10.3 ppm). This
value is below the ACGIH and Occupational safety
and health administration (OSHA) recommended
levels recommended for time weighted average
(TWA) personal exposures. The highest mean concentrations
were for the first four workers [9.2, 10.2,
10.4, and 9.4 ppm, respectively]. Maximum oneminute
xylene concentrations varied from 0.8 ppm
for worker No. 14 to 186.0 ppm for worker No. 2.
Minimum one-minute concentrations varied from
0.0 ppm for worker No. 1 to 0.9 ppm for workers
No. 3, 5, and 6. In spite of the low TWA xylene
concentration in this factory, among some employees
short-term exposure levels (STEL) were higher than
recommended by the ACGIH.17