Lawrence Berkeley National Laboratory

Four unoccupied FEMA temporary housing units (THUs) were studied to assess their indoor emissions of volatile organic compounds including formaldehyde. Measurement of whole-THU VOC and aldehyde emission factors (mu g h-1 per m2 of floor area) for each of the four THUs were made at FEMA's Purvis MS staging yard using a mass balance approach. Measurements were made in the morning, and again in the afternoon in each THU. Steady-state indoor formaldehyde concentrations ranged from 378 mu g m-3 (0.31ppm) to 632 mu g m-3 (0.52 ppm) in the AM, and from 433 mu g m-3 (0.35 ppm) to 926 mu g m-3 (0.78 ppm) in the PM. THU air exchange rates ranged from 0.15 h-1 to 0.39 h-1. A total of 45 small (approximately 0.025 m2) samples of surface material, 16 types, were collected directly from the four THUs and shipped to Lawrence Berkeley Laboratory. The material samples were analyzed for VOC and aldehyde emissions in small stainless steel chambers using a standard, accurate mass balance method. Quantification of VOCs was done via gas chromatography -- mass spectrometry and low molecular weight aldehydes via high performance liquid chromatography. Material specific emission factors (mu g h-1 per m2 of material) were quantified. Approximately 80 unique VOCs were tentatively identified in the THU field samples, of which forty-five were quantified either because of their toxicological significance or because their concentrations were high. Whole-trailer and material specific emission factors were calculated for 33 compounds. The THU emission factors and those from their component materials were compared against those measured from other types of housing and the materials used in their construction. Whole THU emission factors for most VOCs were typically similar to those from comparative housing. The three exceptions were exceptionally large emissions of formaldehyde and TMPD-DIB (a common plasticizer in vinyl products), and somewhat elevated for phenol. Of these three compounds, formaldehyde was the only one with toxicological significance at the observed concentrations. Whole THU formaldehyde emissions ranged from 173 to 266 mu g m-2 h 1 in the morning and 257 to 347 mu g m-2 h-1 in the afternoon. Median formaldehyde emissions in previously studied site-built and manufactured homes were 31 and 45 mu g m-2 h-1, respectively. Only one of the composite wood materials that was tested appeared to exceed the HUD formaldehyde emission standard (430 mu g/m2 h-1 for particleboard and 130 mu g/m2 h-1 for plywood). The high loading factor (material surface area divided by THU volume) of composite wood products in the THUs and the low fresh air exchange relative to the material surface area may be responsible for the excessive concentrations observed for some of the VOCs and formaldehyde.