Written by Tom Hill, Technical Director, Site Development
As our industry continues to evolve, so does our understanding of how materials affect both the environment and public health. One area under increasing scrutiny is the use of coal tar-based sealers—long-time industry standard materials commonly applied to asphalt pavements for durability and appearance. Recently, mounting evidence has shown that these sealants pose serious health and environmental risks, prompting a necessary and responsible shift within our professional practice.
At TERRA, we believe that the choices we make about materials today shape the health of our communities tomorrow. That’s why we’re aligning our practices with the latest science and phasing out coal tar sealers in favor of safer, high-performing alternatives.
Understanding the Risks
Coal tar-based sealers have been widely used for decades to protect and enhance the appearance of asphalt surfaces like driveways, parking lots, and pathways. However, these products contain high levels of polycyclic aromatic hydrocarbons (PAHs)—toxic compounds known to cause cancer and other serious health effects in humans and wildlife.
An expanding range of professional and academic studies have examined the effects of coal tar sealers on the environment and nearby inhabitants. Per usgs.gov—a site committed to sharing information about our environments and the ways they’re impacted by human practices—PAH concentrations in stormwater runoff from coal tar sealed lots were 6,500% that of unsealed lots and toxic to aquatic life. Later studies showed rapid declines in PAH concentrations of public water bodies following sealer bans. The site also emphasizes that children are especially at risk due to their proximity to ground-level surfaces and developing immune systems. Coal tar sealer dust inside homes adjacent to coal tar sealed lots have PAH levels 2,500% higher than those of other homes.
With increased awareness and growing public concern, many cities, counties, states, and home improvement retailers across the US have already taken action to ban or restrict coal tar sealant use.
Time for Alternatives
Fortunately, the pavement sealer industry has brought numerous innovative sealer products to market. Asphalt-based sealers, acrylics, and other innovative products offer reliable surface protection without the toxic side effects of coal tar. In our projects, polymer modified asphalt emulsion sealers have shown to be an effective substitute for price and performance and boast a 99.9% reduction in PAH content.
Here’s why we’re advocating for alternatives:
Healthier for communities: Significantly lower PAH levels make these options safer for people, pets, and ecosystems.
Better for the environment: Reduced runoff toxicity means less impact on stormwater and aquatic life.
Comparable performance: Many alternative sealants now offer similar or even improved durability, UV resistance, and visual appeal.
Compliance: Choosing safer products keeps us ahead of growing regulations and positions us as leaders in sustainable practice.
Making the Change at TERRA
At TERRA, our commitment to stewardship means more than protecting what exists. It’s about building responsibly and minimizing environmental disturbances. Transitioning away from coal tar sealers aligns with our mission to enhance communities and reflects our proactive approach to safer, forward-thinking design.
Our team has refined sets of standards and specifications, as well as training, to promote alternative sealer products and prohibit the use of coal tar sealer products on our projects.
Looking Forward
This transition is just one example of how small changes in material choices can lead to big wins for public health, sustainability, and community trust. As we continue to evolve, we remain committed to challenging tradition and embracing practices that are evolving, safer, and more in tune with the needs of the people and places we serve.
Because at the end of the day, progress isn’t just about innovation—it’s about intention.