A questionnaire concerning lighting conditions was sent to 105 Canadian museums, galleries and archives, along with the request that the institutions submit samples of ultraviolet filters in use. Sixty institutions replied to the questionnaire and 26 sent filter samples, which were tested as to their efficiency in removing ultraviolet radiation. It was found that only 25per thousand of the institutions know what their lighting levels are, and that only 12per thousand of them keep their lighting at acceptable levels. An increasing number of institutions apparently use ultraviolet filters on fluorescent tubes, although no responding institutions reported the use of filters for daylight. A number of ultraviolet filters currently manufactured appear to be excellent, and testing of such filters indicates that they can be used for at least 10 years.