Visual Clearance vs. Dust Wipe Sampling: What's The Difference?

As we approach July 15 when we will find out if, and when, the cleaning verification standards for RRP will change to laboratory analysis and certification, it is becoming more and more confusing to many of us as we try to process the new terms and procedures such as cleaning, verification, sampling, dust testing, XRF analysis, risk assessor, lead inspector, and dust sampling technician.

To begin, when RRP Lead Safe Practices were being debated, there was a concentrated effort to make it easier and less intrusive than HUD or OSHA lead safe practices or abatement procedures, all of which require laboratory analysis of the finished project to ensure the lead was gone.

This brought us the Cleaning Verification Card – the plastic laminated card with the “clear” window so we could check our cleaning cloths to determine if the area was clean enough. That’s how we all were trained when we took the Certified Renovator training.

Under the new standards, lead is considered a hazard if there is greater than:

  1. 40 micrograms of lead in dust per square foot on floors;
  2. 250 micrograms of lead in dust per square foot on interior window sills

This has raised questions as to the reliability of verification visually, and thus the debate that has us all watching the Federal Register for the July 15, 2011 decision.

A quick review of the three procedures (visual, XRF, and sampling) for cleaning verification shows an almost “good, better, best” approach to accuracy. For the purposes of this review we will not discuss exterior RRP where visual is still the method for determining clean for RRP purposes.

Visual Verification relies on the user to determine if the color card comparison indicates sufficient cleaning has been done. There is nothing scientific about it.

XRF analysis, which is using the spectrum analysis gun that records concentration of lead in the surface being touched. This test is accurate, acceptable by all, and can only be done by a Certified Risk Assessor or Lead Inspector. It is best used to determine the presence of lead when you start, not the levels when you leave, and it cannot accurately read dust levels.

Clearance Sampling has two variations: chip sampling and dust sampling. When Chip sampling is used, a piece of the material suspected of containing lead paint, is collected, placed in a sterile bottle and shipped off to a certified lab for analysis. The lab issues a report detailing lead concentration as a function of the chip size. This is to prove whether lead is present (or not) and what the concentration is.

The alternate variation is Dust Sampling, which is also referred to as “wipe sampling”. Special cloth wipes are used to wipe clean a defined area, in a very specific way, to collect residual dust on the wipe. The wipe is also placed in a sterile container to be shipped off to the certified lab for analysis based on concentration (or not) of lead dust for the area wiped. This test is designed to confirm that the lead dust concentration is below the lead hazard standards based on concentration in the area “wiped”.

Here’s a quick review on how each is done:

Visual Clearance
A certified renovator must perform a visual inspection to determine whether dust, debris or residue is still present. If dust, debris or residue is present, these conditions must be removed by re-cleaning and another visual inspection must be performed. After this successful visual inspection, a certified renovator must verify that each windowsill in the work area has been adequately cleaned by wiping the windowsill with a wet disposable cleaning cloth that is damp to the touch. If the cloth matches or is lighter than the cleaning verification card, the windowsill has been adequately cleaned.

If the cloth does not match and is darker than the cleaning verification card, the windowsill must be re-cleaned, and the surface wiped again. If it still doesn’t match, the renovator waits until the sill is dry, wipes with a new dry cloth and calls it clean.

The same is done for uncarpeted floors and countertops and other horizontal surfaces. Wipe once. Wipe twice if needed. Wipe a third time with a dry cloth if needed, and call it clean.

The EPA is proposing the use of Dust Wipe Sampling and Dust Wipe Testing (Dust Lead Loading) for some of the RRP projects it has determined create significant amounts of lead dust above the safe levels. It is very different from Cleaning Verification through visual confirmation, which is the process originally (and currently) required by RRP.

Dust Wipe Sampling
Dust Wipe Sampling is more involved than visual clearance and includes a process to test the area.  The procedure is as follows:
1. Identify areas to be tested.
2. Use two-inch masking tape to outline a square or rectangular surface, which should be a minimum of 16 square inches (e.g., 4” X 4” or 8” X 2”). After sampling is completed note the length and width as well as the units of measurement of tested area, and record it on the sampling form. The laboratory will calculate the concentration of lead in standard units.
3. Loosen the cap of the polyethylene centrifuge tube and place it near the surface to be sampled.
4. Put on clean disposable gloves (use a new pair of gloves for each sample collected.).
5. Remove dust wipe from its packet, open it fully, then refold it in half two times.
6. First Wipe Pass (side-to-side). Being careful to keep wipe within the perimeter of the tape, repeat on the opposite side. Wipe along the top, inside perimeter of tape, then from side to side in as many S-like motions as needed to cover the entire wipe area. At the end of the last ‘S’, sweep toward the middle of the surface and pinch debris into the wipe, folding it once so that contaminants are trapped in the wipe.
7. Second Wipe Pass (top-to-bottom). Repeat the above procedure using the same wipe and S-like motion but at a 90° angle to the first. Fold contaminated side inward again and insert wipe into centrifuge tube (one wipe per centrifuge tube.)
8. Replace cap on tube and close tightly. Label tube. Remove and discard gloves. Record the laboratory number on the chain of custody and describe the sample location completely.
9. After sampling, measure the surface area wiped to the nearest eighth of an inch and record on the chain of custody form.
10. Fill out the chain of custody form completely. Return samples with this form, chain of custody form, to laboratory for analysis.
11. Then, wait for the results.

Paint Chip Sampling
Paint chip samples show the amount of lead in paint. There are two tests:

  1. Atomic Spectrometry shows the volume/or weight of lead in a paint sample, and
  2. The Toxicity Characteristic Leaching Procedure (TCLP) test determines how the lead would leach out in a landfill.

The gathering is accomplished by cutting a piece of the lead paint coating and placing it in a sterile bottle, filling out the paperwork for change of custody and sending it an accredited lab for their report.

XRF Spectrum Analysis
Lead Inspectors and Risk Assessors are the only certified individuals who can use the EXF gun fort analysis of lead paint concentrations. No lab is needed for the report because the gun analyzes on the spot and produces a reading recorded in the gun and on the forms the inspector or risk assessor submits to the client.

Certified Renovators can only perform Visual Clearance. To perform other verification, there must be proper certification.  Dust and samples should be selected and collected by a certified risk assessor, though a paint inspector and dust-sampling technician will be allowed if there is no state or local restriction on the sampling technician.

Analysis of dust and samples using a laboratory must use a laboratory recognized by EPA as NLLAP (National Lead Laboratory Accreditation Program) Certified. XRF analysis can only be done by a Certified Lead Inspector or a Certified Risk Assessor.