2.3 HUD Guidelines and Action Levels

While the EPA writes the legal regulations governing lead-based paint activities, the Department of Housing and Urban Development (HUD) provides the technical methodologies. The HUD Guidelines for the Evaluation and Control of Lead-Based Paint Hazards in Housing (often simply called the HUD Guidelines) is the definitive manual for lead professionals.

For the EPA Lead Inspector exam, you must be intimately familiar with Chapter 7: Lead-Based Paint Inspection. This chapter outlines the statistical sampling methodologies, testing protocols, and standard action levels that determine whether a surface is legally considered to contain lead-based paint.

Standard Federal Action Levels for Lead-Based Paint

The most important numbers you will memorize as a lead inspector are the federal thresholds that define 'lead-based paint.' If the lead concentration on a painted surface meets or exceeds these levels, it is legally classified as lead-based paint.

There are two primary ways to measure lead in paint: area concentration (measured by an XRF) and weight concentration (measured by a laboratory).

1. XRF Analysis (Area Concentration): When using an X-Ray Fluorescence (XRF) analyzer, the federal action level is 1.0 milligrams per square centimeter (1.0 mg/cm²).

• A reading of 1.0 mg/cm² or greater is considered POSITIVE for lead-based paint.
• A reading of 0.9 mg/cm² or lower is considered NEGATIVE (assuming it is outside the inconclusive range, which we will discuss below).

2. Laboratory Analysis (Weight Concentration): When taking a physical paint chip sample and sending it to a recognized laboratory (using methods like Atomic Absorption Spectrometry or Inductively Coupled Plasma Emission Spectrometry), the federal action level is 0.5% by weight.

You must understand how to convert this percentage into other units commonly reported by laboratories. All of the following are equivalent to the federal action level of 0.5% by weight:

• 0.5%
• 5,000 parts per million (ppm)
• 5,000 milligrams per kilogram (mg/kg)
• 5,000 micrograms per gram (µg/g)

(Note: To convert a percentage to ppm, simply multiply by 10,000. 0.5 x 10,000 = 5,000 ppm). If a lab report indicates a sample contains 4,500 ppm of lead, it is considered NEGATIVE under federal standards (though it still contains lead). If it reports 6,000 ppm, it is POSITIVE.

XRF Analyzers: Calibration and Performance Characteristic Sheets

XRF analyzers use a radioactive source (like Cobalt-57 or Cadmium-109) to emit x-rays into a painted surface, causing the lead atoms to emit a characteristic fluorescent energy that the device measures. Because these are complex, radioactive scientific instruments, strict quality control is required.

Calibration Checks: An inspector must perform calibration checks on the XRF instrument to ensure it is reading accurately. According to HUD Guidelines, calibration checks must be performed:

1. At the beginning of the inspection.
2. Every 4 hours during the inspection.
3. At the end of the inspection.
4. If the instrument is turned off and back on.

These checks are performed using a known standard provided by the National Institute of Standards and Technology (NIST), typically a small red block of film with a precise, known lead concentration. If the calibration check fails (reads outside the acceptable tolerance limits), the instrument must not be used, and any readings taken since the last successful calibration check are considered invalid.

Performance Characteristic Sheet (PCS): Every XRF model has a specific Performance Characteristic Sheet developed jointly by HUD and the EPA. The PCS tells the inspector exactly how to operate that specific model of XRF. It provides crucial information, including:

• Whether substrate correction is required (adjusting the reading based on the underlying material, such as wood, brick, or metal, which can sometimes interfere with XRF x-rays).
• The specific inconclusive range for different substrates.

The Inconclusive Range and Substrate Correction

XRF analyzers are highly accurate, but they are not perfect. Sometimes, a reading is so close to the 1.0 mg/cm² threshold that the statistical margin of error prevents a definitive Positive or Negative classification. This is known as the inconclusive range.

For example, the PCS for a particular XRF model might state that on a wood substrate, the inconclusive range is 0.9 to 1.1 mg/cm².

• A reading of 1.2 mg/cm² would be a clear POSITIVE.
• A reading of 0.8 mg/cm² would be a clear NEGATIVE.
• A reading of 1.0 mg/cm² falls directly into the inconclusive range.

When a reading is inconclusive, the inspector cannot make a final determination based on the XRF alone. The HUD Guidelines require that inconclusive readings must be confirmed by taking a physical paint chip sample of that specific testing combination and submitting it to an EPA-recognized laboratory (NLLAP) for quantitative analysis. The laboratory result (using the 0.5% by weight threshold) becomes the final, definitive answer.

Furthermore, older XRF technologies often required substrate correction. Because dense materials like brick and concrete can reflect x-rays and artificially inflate the lead reading, inspectors had to take readings on bare substrate (paint removed) to determine a 'correction value.' This value was then mathematically subtracted from the apparent XRF reading to find the true lead concentration. While many modern XRF instruments internally correct for substrates and do not require manual substrate correction (as dictated by their PCS), you must understand the concept of substrate interference for the exam.

Dust and Soil Hazard Action Levels

While Lead Inspectors primarily focus on paint, they also conduct clearance testing, which involves dust wipes and soil sampling. It is vital to know the hazard thresholds for these media. (Note: The EPA frequently updates dust hazard levels to be more protective. The numbers below represent historical federal standards often tested, but inspectors must always be aware of the most current, stringent EPA or local standards.)

Federal Dust-Lead Hazard Levels (Historical/Standard Testing Reference):

• Floors: 10 micrograms per square foot (µg/ft²)
• Interior Window Sills: 100 micrograms per square foot (µg/ft²) (Important Note: In 2024, the EPA finalized a rule lowering dust-lead hazard standards to any reportable level above zero. However, for many standardized exams, you should recognize the 10/100 thresholds, or specific clearance levels like 10 µg/ft² for floors, 100 µg/ft² for sills, and 400 µg/ft² for window troughs. Always default to the most protective standard applicable in your jurisdiction.)

Federal Soil-Lead Hazard Levels:

• Play areas and child contact areas: 400 parts per million (ppm)
• Bare soil in the remainder of the yard: 1,200 parts per million (ppm)