In Clendenin Brothers, Inc. v. United States Fire Ins. Co., 2006 WL 27432 (Md. Jan. 6, 2006), a Maryland appeals court found that an insurer was not relieved of its duty to defend against a claim for injuries arising from manganese welding fumes by invoking the pollution exclusion.

 Plaintiffs in underlying lawsuits claimed that Clendenin Brothers' welding products produced harmful fumes containing manganese, which caused bodily injury and neurological damage. U.S. Fire sought a declaratory judgment stating that it had no duty to defend or indemnify, based on the total pollution exclusions in the general liability and umbrella policies it issued to Clendenin Brothers.

 The policies' pollutions exclusions stated: "This Insurance does not apply to:…f. (1) 'Bodily Injury' or 'property damage' which would not have occurred in whole or in part but for the actual, alleged or threatened discharge, dispersal, seepage, migration, release or escape or pollutants at any time." The policies defined "pollutants" as "any solid, liquid, gaseous, or thermal irritant or contaminant, including smoke, vapor, soot, fumes, acid, alkalis, chemicals and waste."