The importance of controlling air pollutants to enhance the stability of silver photographic images is generally recognized. American daguerreotypes are generally encased, which protects them from many forms of environmental damage. The author has studied the effects of various materials used in Daguerreotype cases. All the materials used may generate sulfides and possibly cause tarnish formation. Further, as the case's seal breaks down, environmental pollutants gain access to the image. One solution is inserting 3M oxidation arrest paper into the case, although further testing of this procedure is required. Maintaining a tight seal of the case is also important.