This part of ISO14855 specifies a method for determining the ultimate aerobic biodegradability of plasticmaterials under controlled composting conditions by gravimetric measurement of the amount of carbon dioxideevolved. The method is designed to yield an optimum rate of biodegradation by adjusting the humidity, aerationand temperature of the composting vessel.The method applies to the following materials:—natural and/or synthetic polymers and copolymers, and mixtures of these;—plastic materials that contain additives such as plasticizers or colorants;—water-soluble polymers;—materials that, under the test conditions, do not inhibit the activity of micro-organisms present in theinoculum.If the test material inhibits micro-organisms in the inoculum, another type of mature compost or pre-exposurecompost can be used.