1. Continuous Measurements of Indoor-Outdoor Particulate PAH Concentrations in 7 Homes with Application to the Indoor Mass-Balance Model and Prediction Error 14th Annual Conference of the International Society of Exposure Analysis, Philadelphia, PA Paper No. W2A-04 October 21, 2004

2. AUTHORS Wayne Ott Neil Klepeis Paul Switzer Don Rozenberg CONTRIBUTORS George Angus Karen Johnson Lee Langan Peggy McClure Mary Rozenberg Pamela Shreeve Laure Yadon Department of Statistics Stanford University

3. Indoor-Outdoor Model Derived from Mass-Balance Equation Theoretical Basis, Exact Equally-Spaced Time Steps Outdoor Concentrations as Input Only Two Parameters Required Predicted Indoor Concentration Compared with Measured Indoor Concentration

4. Recursive Indoor-Outdoor Model for PM

5. Modeling Approach (Piecewise-Constant Inputs and Piecewise-Exponential Outputs)

6. Persistence Parameter  for Different Combinations of a and k for 1-min Time Step

7. Indoor Persistence Parameter  versus (a + k) for 1-min and 5-min Time Steps

8. METHOD Measure Continuous Outdoor and Indoor Total Particulate PAH (< 1  m) Combustion Sources, Little Humidity Effect Occupied, Nonsmoking Homes Find Optimum Values of ,  Compare Predicted Indoor Concentration with Measured Indoor Concentration For , , Calculate Ranges of a, k, and p

9. Table 1 a Centrally located test home; b 1-min averages; c Area of a single level.

11. Outdoor and Indoor PPAH, New Year’s Day San Francisco House No. 2

12. Arbitrary Parameters Optimal Parameters

13. Error Surface for Indoor Model Prediction Versus Indoor Measurement at San Francisco House No. 2 ( 1-min step time for 3.5 days)

14. Error Surface for Data at Redwood City House 1994 - 1995 (17.5 days, 5-min time step)

15. Error Surface Slices at Fixed Alpha Values

16. Indoor Predicted vs. Indoor Measured at Redwood City House, 17-1/2 Days

17. Measured Outdoor, Measured Indoor PPAH Predicted Indoor, Measured Indoor PPAH

18. Table 2

20. Table 3

21. Table 4

22. Predicting indoor particle concentrations of ambient origin using the mass balance model requires only two parameters,  and . Using three parameters a, k, and p in the indoor mass balance model is algebraically redundant. DISCUSSION DISCUSSION

23. CONCLUSIONS Continuous Indoor-Outdoor PPAH Measurements in 7 Occupied Homes Field Study Covered 10 Years Indoor Model-Predicted Agreed Well with Indoor Measured at All Homes Fireplaces and Wood Burning were the Major Sources of Ambient Particulate PAH Motor Vehicles were a Minor Source Indoor Model with 3 Parameters (a, k, and p) is Over-specified