Formaldehyde and other volatile organic chemical emissions in four FEMA temporary housing units

Indoor concentrations of 33 volatile organic chemicals were measured in four unoccupied temporary housing units (THUs) belonging to the U.S. Federal Emergency Management Administration (FEMA). The highest level contaminants in the THUs include formaldehyde, acetic acid, and 2,2,4-trimethyl-1,3-pentanediol diisobutyrate (TXIB) with median concentrations of 440, 425, and 36 ppb, respectively. A number of volatile organic compounds (VOCs) were higher than published concentrations in other dwellings, but whole THU emission factors for most chemicals were either lower than or similar to values reported for newly constructed homes. However, several chemicals exceeded previously measured new building emission rates by over a factor of 5. Materials were collected from the THUs, and emission factors were determined using small chambers to identify the potential source of indoor contaminants. The individual materials were grouped by material type, and emissions were used to derive exposure concentrations for comparison to reference values. Using material loading factors and ventilation rates that are relevant to the trailers, all of the material types we tested had at least two chemicals (formaldehyde and nonanal) with derived concentrations in excess of chronic reference exposure levels or odor thresholds. The extensive use of composite wood products, sealants, and vinyl coverings, combined with the low air exchange rates relative to material surface areas, may explain the high concentrations of some VOCs and formaldehyde.