Is An Insurer Required to Defend and Indemnify the Insured In a CGL Policy Regarding Exclusion of Carbon Monoxide Poisoning Even if it is Not Specifically Excluded ? In Andersen v. Highland House Co., 93 Ohio St.3d 547, 2001 Ohio 1607, 757 N.E.2d 329, the Supreme Court of Ohio determined that where in a CGL policy a pollution exclusion did not specifically exclude residential carbon monoxide poisoning, and where, based on the facts of the case, the insured reasonably believed that the policy did not exclude such claims, the insurer was required to defend and indemnify the insured. In Andersen, the court first determined that the pollution exclusion was ambiguous because carbon monoxide was not specifically listed. Next, the court examined the historical purpose of the pollution exclusion and determined that it was reasonable for the insureds to believe that the policy did not exclude claims for injuries resulting from carbon monoxide leaks. Id. at 550. The court also noted the importance of construing ambiguities in favor of the insured. Id. at 551. Further, although it declined to determine the merits of the reasonable-expectations doctrine, the court noted that it could apply to the case. Id.