Field Derived Emission Factors For Formaldehyde and other Volatile Organic Compounds in FEMA Temporary Housing Units
Sixteen previously occupied temporary housing units (THUs) were studied to assess emissions of volatile organic compounds. The whole trailer emission factors were evaluated for 36 VOCs including formaldehyde. Indoor sampling was carried out in the
THUs located in Purvis staging yard in Mississippi, USA. Indoor temperature and relative humidity (RH) were also measured in all the trailers during sampling. Indoor temperatures were varied (increased or decreased) in a selection of THUs using the
heating, ventilation and air conditioning (HVAC) systems. Indoor temperatures during sampling ranged from 14º C to 33º C, and relative humidity (RH) varied between 35% and 74%. Ventilation rates were increased in some trailers using bathroom fans and
vents during some of the sampling events. Ventilation rates measured during some a selection of sampling events varied from 0.14 to 4.3 h-1. Steady state indoor formaldehyde concentrations ranged from 10 μg-m-3 to 1000 μg-m-3. The formaldehyde concentrations in the trailers were of toxicological significance. The effects of temperature, humidity and ventilation rates were also studied. A linear regression model was built using log of percentage relative humidity, inverse of temperature (in K-1), and inverse log ACH as continuous independent variables, trailer
manufacturer as a categorical independent variable, and log of the chemical emission factors as the dependent variable. The coefficients of inverse temperature, log relative humidity, log inverse ACH with log emission factor were found to be statistically significant for all the samples at the 95% confidence level. The regression model was found to explain about 84% of the variation in the dependent variable. Most VOC concentrations measured indoors in the Purvis THUs were mostly found to be below values reported in earlier studies by Maddalena et al.,1,2 Hodgson et al.,3 and Hippelein4. Emissions of TMPB-DIB (a plasticizer found in vinyl products) were found to be higher
than values reported in comparable housing by Hodgson et al.,3. Emissions of phenol were also found to be slightly higher than values reported in earlier studies1,2,3. This study can assist in retrospective formaldehyde exposure assessments of THUs where
estimates of the occupants indoor formaldehyde exposures are needed.