This section is provided to permit the classification of environmental events, circumstances, and conditions as the cause of injury, poisoning, and other adverse effects. Where a code from this section is applicable, it is intended that it shall be used in addition to a code from one of the main chapters of ICD-9-CM, indicating the nature of the condition. Certain other conditions which may be stated to be due to external causes are classified in Chapters 1 to 16 of ICD-9-CM. For these, the "E" code classification should be used as an additional code for more detailed analysis.

Machinery accidents [other than those connected with transport] are classifiable to category E919, in which the fourth digit allows a broad classification of the type of machinery involved.

Categories for "late effects" of accidents and other external causes are to be found at E929, E959, E969, E977, E989, and E999.