Researchers have completed a multi-season study of ventilation and indoor air quality in 108 new homes in California. ARB and the California Energy Commission sponsored the study, which was conducted by a team led by Indoor Environmental Engineering. The team found that new, single-family detached homes in California were built relatively airtight, and had very low outdoor air exchange rates. In addition, indoor concentrations of formaldehyde often exceeded health-based exposure guidelines for air contaminants indoors, due to the many indoor sources of formaldehyde. Indoor concentrations of a few other chemicals such as benzene, naphthalene, and 1,4-dichlorobenzene also exceeded exposure guidelines in some cases. The ARB has adopted limits on formaldehyde emissions from composite wood products, which will help reduce indoor formaldehyde levels in new homes. Reduction of formaldehyde emissions from other indoor sources also is needed. In part due to the results of this study, the Commission approved a regulation requiring mechanical ventilation systems in all new homes starting in 2010; such systems provide a continuous supply of outdoor air, thus improving the outdoor air exchange rate and reducing indoor contaminant levels.
Contact Tom Phillips (tphillip(at)arb.ca.gov, 916.322.7145) for inquiries about the report. If you have problems accessing the report website or the report, contact Susan Lum (slum(at)arb.ca.gov, 916.323.5043).
RBc: We support this, "...a continuous supply of outdoor air, thus improving the outdoor air exchange rate and reducing indoor contaminant levels." ...providing that the outdoor air is also of good quality.