1. Formaldehyde Emission Modeling in Manufactured Homes Jacqueline Bayer 1, Dr. Patrick Gurian 2, and Dr. Jin Wen 2 1 BS/MS Student, Dept. of Civil, Architectural, and Environmental Engineering, Drexel University 2 Dept. of Civil, Architectural and Environmental Engineering, Drexel University METHODS 1300 SF home floor plan, shown in Figure 1, and CONTAM model obtained from NIST study 3 Ventilation provided by forced air HVAC system, bathroom and kitchen exhaust fans, and passive vents Base case - all windows and vents closed and HVAC and exhaust fans off for entire year Philadelphia, PA base case location Dual emission factor and time constant model used in simulation 4 EF = EF 01 e -k1t + EF 02 e -k2t EF obtained from field monitoring studies 4,5 Exposure and risk calculated using the EPA IRIS database Risk distributed over 70 years Worst case exposure – 24 hours spent in home Typical case exposure - 14 hours spent in home BACKGROUND Formaldehyde exposure can cause sensory irritation, fatigue, sore throat, and cancer Symptoms can begin to occur between 0.1 to 0.46 ppm 1 ASHRAE cites a never-to-exceed formaldehyde concentration as 0.027 ppm for an eight-hour duration period Manufactured homes have a high concentration of pressed wood products containing formaldehyde ASHRAE ventilation standard, 0.35 h -1, is not met in most manufactured homes because of tighter construction techniques 2 Variety of factors can affect formaldehyde levels indoors – weather and wind patterns, vapor pressure, and air exchange rates No study currently exists that compares formaldehyde exposure in modular homes with potential mitigation solutions CONTAM airflow simulation software was used to model formaldehyde mitigation solutions in a manufactured home RESULTS Air exchange rates averaged below ASHRAE value – 0.263 h -1 BASE CASE - yielded results of above ASHRAE never-to- exceed levels Highest monthly average formaldehyde concentrations found in master bedroom closet: 0.55 to 0.78 ppm Bedroom concentrations: 0.07 to 0.09 ppm Hall bath average concentration: 0.14 to 0.26 ppm (Figure 2) Hall bath exhaust fan on simulation greatly reduced concentration: 0.038 to 0.07 ppm (Figure 3) RISK RESULTS Worst case: 1.6 x 10 -5 Typical case: 1.1 x 10 -5 OBJECTIVES Research formaldehyde exposure effects and standards Determine appropriate emission rate model for simulation Calculate area of formaldehyde-emitting surfaces in each room Complete CONTAM base case model scenario Calculate exposure and risk for typical and worst case occupancy scenarios Formulate scenarios and calculation framework for additional modeling FUTURE RESEARCH Run simulation varying home location, ventilation method, and filtration technique Calculate risk for additional scenarios Complete cost-benefit analysis to find optimal solution based on home location REFERENCES 1. Kilburn, K (2000) "Indoor Air Effects after Building Renovation and in Manufactured Homes." The American Journal of the Medical Sciences, 320: 249+. 2. Hodgson, A, et al. (2000) "Volatile Organic Compound Concentrations and Emission Rates in New Manufactured and Site-Built Homes." Indoor Air, 10: 178+. 3. Persily, A, et al. (2004) “Ventilation Characterization of a New Manufactured House.” National Institute of Standards and Technology. 4. Brown, S (1999) “Chamber Assessment of Formaldehyde and VOC Emissions from Wood-Based Panels.” Indoor Air, 9: 209-215. 5. Kelly, T, et al. (1999) “Emission Rates of Formaldehyde from Materials and Consumer Products Found in California Homes.” Environmental Science and Technology, 33: 81-88. Figure 1. Home floor plan Figure 2. Base case – hall bath Figure 3. Exhaust fan – hall bath