Coal tar sealers are protective coatings used primarily on asphalt surfaces, such as driveways and parking lots. They are made from a byproduct of coal processing and help to seal and protect the asphalt from damage caused by weather, UV rays, and vehicle traffic. These sealers can enhance the appearance of the surface, giving it a glossy finish. However, there are environmental concerns associated with coal tar sealers. They contain polycyclic aromatic hydrocarbons (PAHs), which can be harmful to human health and aquatic life. As a result, some regions have restricted or banned their use in favor of safer alternatives.