Pollution is the stuff that resulted from factories in the mid 20th century not knowing how to properly dispose of chemical waste.
Under the written terms of a standard general liability policy, pollution is way more broad. And damage from pollutants is excluded from coverage.
So, many courts abrogated the effect of the pollution exclusion to apply only to environmental pollution. This is very jurisdictionally specific. In Indiana, the exclusion might as well not be written. In Florida, the exclusion is applied quite broadly.
In response to the courts, the insurers added the Total Pollution Exclusion, an endorsement that is written stronger and more specifically than the standard exclusion.
I successfully litigated the TPE in Cincinnati Ins. Co. v Roy’s Plumbing (and wrote my first LinkedIn article about it). That case was about toxic sludge accidentally unearthed by a plumbing company. Applying New York law, the federal court held that my client owed no coverage. The decision was subsequently upheld on appeal.