He thought he'd checked all the boxes. The heat gun told a different story.

He was a scientist. An entomologist by training. He knew about airflow. He knew about respirators. He even knew about lead.

What he did not know was that a heat gun at 400°C vaporizes lead paint into a particulate that a dust mask cannot stop. The vapor passes right through the mesh. The respirator he was wearing, the one rated for the kind of dust you would expect from sanding, was the wrong respirator for what he was actually doing.

He was stripping the paint off a heritage boatshed. A weekend project. He had checked all the boxes a smart person would check. A neighbor mentioned the LEAD Group, casually, over the fence. He went and got a blood test on a hunch.

Elevated.

No shame in not knowing. Plenty of shame in not finding out.

Why a heat gun is the worst tool for the job

Lead paint releases lead three different ways depending on what you do to it. Sanding it makes a coarse dust your N95 will mostly stop. Scraping it makes flakes you can sweep up. Heating it past about 370°C vaporizes the lead pigment, and that vapor cools into a sub-micron particulate that passes through every mask short of a sealed P100 with a HEPA cartridge.

The standard EPA RRP guidance is explicit on this, do not use an open-flame torch or a high-heat gun on lead paint. Most weekend renovators have either never read it or have read it and assumed their dust mask was enough. It is not.

Anything older than 1978 is suspect, including the boatshed

Lead paint was banned for residential use in the United States in 1978. Marine and outbuilding paint kept lead in the formula years after that, and the boatsheds, barns, fences, and porches built before the ban were painted with whatever was on the shelf at the time. If the paint is original, assume it is leaded until a test says otherwise.

The places to suspect first:

Painted wood that has weathered for decades

Heritage boatsheds, sash windows, exterior porches, shutters, fascia, fences. Anywhere the paint has been chalking for forty years is releasing lead at the surface every time it rains.

Hardware and trim

Brass cleats, hinges, latches, and fittings on old buildings often carry their own lead, both from leaded brass alloys and from the paint that was used to coat them.

Anything you are about to renovate

The dust raised during demolition is the single highest-exposure event in the entire life of an old building. Test before the saw comes out, not after.

Test first, then decide what to do

The decision tree is short, but it has to happen in the right order:

The part nobody talks about, your kids and grandkids

If children visit the property while you are working on it, the calculus changes. Children under six absorb four to five times more lead per dose than adults. They put hands in their mouths. The dust on the porch boards becomes the dust on their fingers becomes the dose on their tongue.

If you are stripping a heritage boatshed and the grandchildren come to visit on weekends, the answer is either to test and contain before they arrive, or to keep them out of the work zone entirely until the dust is gone.

You cannot see lead-paint dust. You can make it visible, in 30 seconds, with a UV light and a spray that costs less than dinner.

What to do this week

If you take nothing else from this article, take these three steps:

1. Stop using a heat gun on any paint older than 1978 until you have tested it. A chemical stripper, used wet, with a P100 respirator, is the safer default.

2. Test the paint, not just one spot. Old buildings have been touched up dozens of times. Test the original layer underneath, that is where the lead lives.

3. If you have already done unprotected stripping, ask for a blood-lead test. Mention the project. Mention the heat gun. Get a baseline so you have something to compare to in three months.

You did not choose to inherit a building painted in the leaded-paint era. You can choose what happens before the heat gun comes out.