Growing prosperity and urbanization could double the volume of municipal solid waste annually by 2025, challenging environmental and public health management in the world’s cities, according to new research conducted by the Worldwatch Institute (www.worldwatch.org) for its Vital Signs Online service. Although some of this waste is eventually recycled, the doubling of waste that current projections indicate would bring the volume of municipal solid waste—or MSW—from today’s 1.3 billion tons per year to 2.6 billion tons, writes report author and Worldwatch Senior Fellow Gary Gardner. As defined in the report, MSW consists of organic material, paper, plastic, glass, metals, and other refuse collected by municipal authorities, largely from homes, offices, institutions, and commercial establishments. MSW is a subset of the larger universe of waste and typically does not include waste collected outside of formal municipal programs. Nor does it include the sewage, industrial waste, or construction and demolition waste generated by cities. And of course MSW does not include rural wastes. MSW is measured before disposal, and data on it often include collected material that is later diverted for recycling. MSW tends to be generated in much higher quantities in wealthier regions of the world. Members of the Organisation for Economic Co-operation and Development (OECD), a group of 34 industrialized nations, lead the world in MSW generation, at nearly 1.6 million tons per day. By contrast, sub-Saharan Africa produces less than one eighth as much, some 200 million tons per day.