To reduce the bulk of solid waste burning of paper, plastic, and other components is often resorted to, either in open dumps or incinerators. Fly ash, noxious gases, and chemical contaminants can thus be released into the air (see air pollution). However, new techniques for "scrubbing" pollutants from incinerator stacks are being developed. Incineration of typical garbage reduces its weight and volume by as much as 80%. Approximately 15.9% of municipal solid waste is combusted.