Dust Settling on Outside Patio or Furniture?

I was sitting on my porch in San Francisco watching kids play on the wooden deck and started to wonder, “is the dust on my porch contaminated with lead dust? If so, how best to clean it up?” So I did a little experiment and tested for lead dust before and after three different cleaning scenarios. This quick experiment demonstrated there is good reason behind the EPA’s recommended lead cleaning protocols.

How much lead is too much?

The U.S. government defines lead–based paint (LBP) as, “any paint, surface coating that contains lead equal to or exceeding 1.0 mg/cm2 or 0.5% by weight.” The exterior of my 1890’s earthquake cottage in San Francisco is covered in lead-based paint (LBP.)

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You can see my exterior paint has a high lead content as measured by my XRF analyzer with a reading of 15 mg/cm2. (XRF, X-ray fluorescence, is a non-destructive technique used to find how much lead is in paint.) We recently bought a new XRF gun for Healthy Building Science and I love this
! It is a great way to quickly screen for lead paint in a building.

The exterior paint on my home is in pretty good condition (no paint chips!), but I was curious to see if there was a lead dust hazard on the wood of my back deck. If the wood is contaminated with lead, what is the best way to clean it up?

Summary of EPA Lead Abatement Protocol

The EPA recommends a combination of HEPA vacuuming followed by wet wiping with detergent, then repeating.

Does this combination really work? I decided to test this for myself. I took four dust wipe samples from my back deck:

for your home and office. The combination of inspections, testing and regular maintenance is effective at identifying problems early and minimizing risks.

Lead Dust Cleaning Study Results

The results undeniably prove the technique works! No lead was detected after the final complete round of HEPA vacuum, wet-wipe and repeat HEPA vacuum, wet-wipe.

Results in microgram per square foot

1 Control
1200 μg/ft²


2 HEPA
96 μg/ft²


3 HEPA vacuum and wet wipe
14μg/ft²


4 HEPA vacuum and wet wipe repeat HEPA vacuum and wet wipe

>10 μg/ft² Undetected!

EPA Recommendations for Controlling Lead Hazards

from the EPA for protecting people from lead hazards:

To learn more about EPA’s requirements for RRP projects visit their


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