In The I.S.O. Pollution Exclusion: How Far Does It Go?, insurance expert witness Dale C. Crawford writes:
Anyone involved in insurance dispute resolution will sooner or later come across an issue involving pollution exclusions. Most carriers-even those operating on a non-admitted basis-use the Insurance Services Office standard form. Typically, the conflict will be whether a cause of loss falls within the exclusionary language.
When these exclusions first evolved in the early 1970s, those active in the industry at the time will recall the two significant features addressed. The first was that damage from pollution was excluded unless it was sudden and accidental; second, the focus was on costs to remediate air, land or water damaged by the pollutants. Thus the intentional polluter who contaminated large land areas or streams over many years or habitually released noxious airborne chemicals would not have coverage for the costs of cleanup. Insurers soon found that the requirement for sudden and accidental was often given wide latitude in favor of coverage. The different terms adopted across the industry were gradually tightened and narrowed into more standard forms, ultimately resulting in a standard ISO form in 1985 with an absolute exclusion.