The NSW EPA classifies waste in the following order, ranging from the least harmful to the most harmful to the environment inert, solid, industrial, and hazardous. The inert waste type is the least likely to undergo "Environmentally Significant Transformations" and, therefore, should not release significant quantities of greenhouse gases or leachates contaminated with nutrients and/or chemicals. Infectious Waste Any waste from sources known to have, or suspected of having, a communicable disease unless treated to a standard acceptable to the NSW Health Department. The extent and duration for which this waste is regarded as infectious waste will depend on the particular infection, the state or type of the disease and, in some cases, the effect of specific treatment and should be based on a consideration of the known modes of transmission of the organisms involved.
Waste not undergoing significant physical, chemical or biological changes following disposal, as it does not adversely affect other matter that it may come into contact with, and does not endanger surface or groundwater.