Changes in VOC Emission Factors with Time in Manufactured Houses
The manufactured houses were sampled on three occasions approximately 2, 4 and 9.5 months after their completion. Temporal changes in the emission factors of 8 individual VOCs in the 4 houses are shown in Figure 3. These compounds were selected to represent different chemical classes, vapor pressure and sources. Only several compounds showed a substantial and consistent decrease in emission factor over time. The formaldehyde emission factor was nearly constant over time in one house and varied by less than a factor of two in the other three houses. In all 4 houses, the acetic acid emission factor increased with time. These results indicate that the sources of VOCs of interest due to their potential odor or irritation effects can persist for relatively long periods (i.e., months) after a house is completed.

Figure 3. Temporal changes in the area-specific emission rates of 8 VOCs in the 4 new manufactured study houses. (LBNL-43519)