What technical and regulatory differences distinguish asphalt emulsion sealers from coal tar sealers?

Asphalt emulsion sealers use asphalt binder dispersed in water, while coal tar sealers use refined coal tar pitch chemistry that can contain higher levels of PAHs. Many jurisdictions regulate or ban coal tar sealers due to environmental concerns, especially runoff into waterways. Technically, coal tar often offers strong resistance to petroleum spills, but it can be more hazardous and has higher regulatory burden. Asphalt emulsions are generally lower odor and lower toxicity, and they fit better with VOC restrictions. Contractors must adjust expectations on chemical resistance and ensure correct film thickness and cure.