| Table 3-5. Formaldehyde concentration after repeated turning of CCP sheets in a test chamber[1] | |
| Rate of turning and total number of sheets in chamber | Average formaldehyde concentration (ppm) |
|---|---|
| 2 sheets/min: | |
| 24 | 0.089 |
| 48 | 0.165 |
| 72 | 0.171 |
| 6 sheets/min: | |
| 72 | 0.081 |
| 144 | 0.102 |
| 216 | 0.212 |
| 288 | 0.501 |
Adapted from Hazelton Laboratories [1985].
- ↑ The indicated number of sheets placed in the chamber, turned at the stated rate, and repackaged. Air samples were then collected from the chamber.
the number of exposed sheets increased. Another test (Table 3-6) was performed to determine whether the rate of turning would affect the final concentration of formaldehyde in the test chamber immediately after turning and 60 and 90 min after turning. When measured immediately after turning, concentrations decreased as the turning rate increased. But concentrations varied little when measured 60 and 90 min after the tests. This result indicates that the rate-limiting factor for total formaldehyde released from CCP is the amount of time spent equilibrating with the environment.
The final test method evaluated was an emission rate study. In this study, 120 sheets of paper were placed in the chamber and turned at a rate of 4 sheets/min. Short-interval sampling began with the initiation of the page turning and continued for 90 min (Table 3-7). The chamber air achieved a constant formaldehyde concentration in less than 30 min. The initial rate of formaldehyde release was 0.098 Mg/sheet per min. This rate was calculated from the first sample by considering the 0.310-μg/L concentration as the midpoint concentration between 0 μg/L and equilibrium, and by assuming an approximately linear increase in the airborne concentration of formaldehyde over the 15-min sampling period.
Product testing. Three replicate sets of eight types of CCP were tested by placing 60 sheets of CCP in the chamber and turning them at a rate of 4 sheets/min. They remained stacked in the chamber for 15 min and were then returned to the foil packages for the duration of the air sampling, which was conducted for 20 min at a rate of approximately 0.5 L/min. The airborne concentrations of formaldehyde in the test chamber averaged from 0.009 to 0.693 ppm (Table 3-8). Little formaldehyde would be expected from the CF since it contains no microcapsules. All types of the CB and CFB with black ink produced higher average formaldehyde concentrations than did the blue ink counterpart. The self-contained samples yielded the highest formaldehyde
