At issue on appeal are two CGL policies issued by National Union Fire Insurance Company of Pittsburgh, PA, to Griffith Foods, covering the periods from September 30, 1983, to September 30, 1985. Each policy included a standard-form pollution exclusion, which bars coverage for: “bodily injury or property damage arising out of the discharge, dispersal, release or escape of… toxic chemicals, liquids or gases, waste materials or other irritants, contaminants or pollutants into or upon land, the atmosphere or any water course or body of water; but this exclusion does not apply if such discharge, dispersal, release or escape is sudden and accidental.”