Implementation of Source Reduction Practices for Volatile Organic Compounds in Manufactured House Construction: Pilot Demonstration Project
Indoor air quality (IAQ) in new houses, particularly occupant's inhalation exposure to toxic, irritant and odorous chemicals, has received comparatively little attention among house builders and product manufacturers. The volatile organic compounds (VOCs) of potential concern in new houses include formaldehyde, acetaldehyde, acetic acid and naphthalene. These VOCs are emitted by a variety of wood products and other materials used to finish the interiors of most houses. This study sought to demonstrate the efficacy of several low-cost measures intended to reduce the emissions and concentrations of formaldehyde and other VOCs in the production of a single manufactured house. The study was conducted as a collaborative effort with a nationwide producer of such houses. Two doublewide houses were selected for study. One received modifications to the cabinetry and countertop materials, a weatherization barrier under a low-emitting carpet system, and low VOC-impact interior paints. The other, produced at about the same time, did not have IAQ modifications and served as the control. The houses were installed on nearby lots in a sales center and were decorated for use as model homes. Samples for formaldehyde, acetaldehyde and other VOCs were collected in the houses at approximately three and six months after they were fully operational. Outdoor air ventilation rates also were measured. The emission rates of higher molecular-weight aldehydes and terpene hydrocarbons predominantly associated with the plywood subfloor were reduced in the modified house likely due to the use of the weatherization barrier. The low-VOC paints substantially reduced the concentration of a major volatile component of interior wall paints. However, the concentrations and emissions of formaldehyde unexpectedly were higher in the modified house (e.g., the emission rate was a factor of two higher). The remainder of the study was spent diagnosing this difference. The heating and air conditioning system was eliminated as a possible source. Measurements of formaldehyde emissions from the particleboard components of the furnishings revealed that the new wood furniture purchased to decorate the modified house, but not the control house, was the likely source of the excess formaldehyde emissions. When approximately adjusted for the emissions from the new furniture, the formaldehyde emission rate in the modified house was nearly equivalent to rate in the control house. This emission rate resulted in formaldehyde concentrations below 50 ppb in the control house.