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Coal-Tar vs. Asphalt-Emulsion Sealcoat: What to Use

Nearly all sealcoat is one of two products: coal-tar or asphalt-emulsion. They look alike going down, but they are very different materials, and the difference reaches into health, the environment and where the law even lets you use them. Here is what separates the two.

The PAH Difference Is Not Small

The whole gap comes down to polycyclic aromatic hydrocarbons, or PAHs. Coal-tar sealcoat carries staggering PAH levels. U.S. Geological Survey research measured PAH concentrations in coal-tar sealcoat products at around 66,000 milligrams per kilogram, against roughly 50 for a typical asphalt-emulsion product. Coal tar and its pitch are classified as known human carcinogens, and studies have tied coal-tar-sealed pavement to sharply higher PAH levels in nearby house dust and to increased cancer risk for the people living beside it.

Why Does It Matter in Central Florida?

PAHs do not stay put on the pavement. They wash off with stormwater and are toxic to fish and aquatic life, which is a genuine concern in a region laced with lakes, wetlands and interconnected water bodies like the ones ringing Kissimmee and the wider Orlando metro. U.S. Geological Survey research found that across 40 urban lakes, coal-tar sealcoat was the single largest source of PAHs in the bottom sediment, contributing about half of the total. That profile is exactly why coal-tar sealants have been banned across a growing list of states and local jurisdictions, even with no federal ban on the books yet.

What We Use

  • Asphalt-emulsion sealer: a blend of asphalt, water and additives that carries a small fraction of the PAHs of coal tar. It is the environmentally preferable choice, and it is the one we apply.
  • The same protection: emulsion still shields the binder from water, oil and UV and restores the deep-black, slip-resistant finish a commercial lot needs.
  • Fewer restrictions: choosing emulsion keeps you clear of the coal-tar bans spreading across the country and the stormwater headaches that ride along with them.

We sealcoat commercial lots with asphalt-emulsion sealer, applied on the right schedule for the Central Florida climate. Request a sealcoating quote and we will scope your lot.

What Are PAHs, and Where Do They Go?

PAHs, polycyclic aromatic hydrocarbons, are a family of compounds that form when coal tar is produced. They do not break down quickly, and they do not stay locked in the pavement. Foot traffic and tires grind a sealed coal-tar surface into fine dust, and the USGS measured PAH in that dust at roughly 1,000 times the level found on lots with other surfaces. The dust tracks indoors: in apartments beside coal-tar-sealed lots, researchers found house-dust PAH about 25 times higher than in apartments next to other pavements, a median of 129 against 5.1 micrograms per gram, with the greatest exposure and cancer risk falling on young children. Rain does the rest, carrying PAH-laden particles off the surface and into the storm system.

How the Two Sealers Compare

  • Coal-tar sealer: refined from coal tar, high in PAHs and classified as a known human carcinogen. It is banned in more than 100 U.S. jurisdictions.
  • Asphalt-emulsion sealer: a blend of asphalt, water, silica sand, polymer additives and fillers, carrying a small fraction of the PAH load. Environmentally preferred and free of coal-tar restrictions.
  • Same look, different risk: the two are hard to tell apart on the pavement, but only coal tar brings the PAH load, the carcinogen classification and the stormwater toxicity.

Does Choosing Emulsion Change the Job?

The application does not change. Emulsion goes down the same way, a minimum of two thin coats over a clean, dry surface, and holds the same two-to-three-year schedule as any commercial seal. You get the protection without the PAH load, without the carcinogen exposure for the people who use the lot, and without the risk of running afoul of a coal-tar ban. For a property near Central Florida's lakes and wetlands, that is the straightforward call.

Common Questions

  • Is coal-tar sealer banned in Florida? There is no statewide Florida ban, and coal-tar rules are set jurisdiction by jurisdiction, with more than 100 U.S. jurisdictions now prohibiting it. We apply asphalt emulsion on every lot, which keeps the question off the table.
  • How much more PAH does coal tar carry? A lot. Coal-tar sealcoat tests around 66,000 milligrams of PAH per kilogram against roughly 50 for asphalt emulsion, and dust worn off a coal-tar lot runs about 1,000 times higher in PAHs than dust off other surfaces.
  • Why does this matter more in Central Florida? The region is laced with lakes and wetlands, and PAHs wash off coal-tar pavement with stormwater. The USGS found coal-tar sealcoat to be the largest PAH source in the sediment of the urban lakes it studied, so the stakes are higher here, where so much of that runoff ends up in open water.
  • What sealer do you use? Asphalt-emulsion sealer, which carries a tiny fraction of coal tar's PAHs and is the environmentally preferable choice for lots near water.

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