Technological and industrial history of 20th-century Canada the Keele Valley Landfill was operated by the City of Toronto from 1983 until 2002, when it was closed because it was full. Chlorofluorocarbons (CFCs), the gas propellants used in aerosol spray cans, became a target for environmental concern in the 1970s and 1980s when research demonstrated that they had a harmful effect on the ozone layer in the atmosphere. The international Montreal Protocol of 1989 banned the use of these substances and they were subsequently replaced with volatile hydrocarbons. The problem with choice to reuse is still not available. There are many products that don't need to be recycled
Radium, and other radioactive substances red glass windows while the disease went through certain stages. Radium, and other radioactive substances Radium, and Other Radio-active Substances; Polonium, Actinium, and Thorium is a book published in 1903 by William Joseph Hammer, when he was about 50 years old. The book is the text of a lecture delivered at a meeting of the American Institute of Electrical Engineers. The title of the lecture was "Radium and other radioactive substances with a consideration of phosphorescent and fluorescent substances. The properties and applications of selenium and the treatment of disease by the ultra violet light". The lecture was augmented by