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HEURESIS PCS December 2015 BACKGROUND INFORMATION EVALUATION DATA SOURCE AND DATE: This sheet is supplemental information to be used in conjunction with Chapter 7 of the HUD Guidelines for the Evaluation and Control of Lead-Based Paint Hazards in Housing ("HUD Guidelines"). Performance parameters shown on this sheet are calculated using test results on building components in the HUD archive. Testing was conducted on 146 test samples in November 2015, with two separate instruments running software version 2.1-2 in Action Level test mode. The actual source strength of each instrument on the day of testing was approximately 2.0 mCi; source ages were approximately one year. OPERATING PARAMETERS Performance parameters shown in this sheet are applicable only when properly operating the instrument using the manufacturer's instructions and procedures described in Chapter 7 of the HUD Guidelines. XRF CALIBRATION CHECK: The calibration of the XRF instrument should be checked using the paint film nearest 1.0 mg/cm2 in the NIST Standard Reference Material (SRM) used (e.g., for NIST SRM 2579, use the 1.02 mg/cm2 film). If the average (rounded to 1 decimal place) of three readings is outside the acceptable calibration check range, follow the manufacturer's instructions to bring the instrument into control before XRF testing proceeds. SUBSTRATE CORRECTION VALUE COMPUTATION: Chapter 7 of the HUD Guidelines provides guidance on correcting XRF results for substrate bias. Supplemental guidance for using the paint film nearest 1.0 mg/cm2 for substrate correction is provided: XRF results are corrected for substrate bias by subtracting from each XRF result a correction value determined separately in each house for single-family housing or in each development for multifamily housing, for each substrate. The correction value is an average of XRF readings taken over the NIST SRM paint film nearest to 1.0 mg/cm2 at test locations that have been scraped bare of their paint covering. Compute the correction values as follows: Using the same XRF instrument, take three readings on a bare substrate area covered with the NIST SRM paint film nearest 1 mg/cm2. Repeat this procedure by taking three more readings on a second bare substrate area of the same substrate covered with the NIST SRM. Compute the correction value for each substrate type where XRF readings indicate substrate correction is needed by computing the average of all six readings as shown below. For each substrate type (the 1.02 mg/cm2 NIST SRM is shown in this example; use the actual lead loading of the NIST SRM used for substrate correction): Correction value = 0st+ 2nd + 3rd + 4th + 5th + 6th Reading)/6 - 1.02 mg/cm2 Repeat this procedure for each substrate requiring substrate correction in the house or housing development. EVALUATING THE QUALITY OF XRF TESTING: Randomly select ten testing combinations for retesting from each house or from two randomly selected units in multifamily housing. Conduct XRF re-testing at the ten testing combinations selected for retesting. Page 2 of 4