Prior Industries classification was into "Red," "Orange" and "Green" classification to work with choices connected with the area of these industries just as with the end goal of approval/consent mechanism. Classification depended on the size of the entities, and the pollution caused because of the release of effluents was not thought of. Later on, industrial areas were arranged based on the pollution index. Pollution Index (PI) of any Industrial Sector means number from 0 to 100 and expanding worth of PI signifies the expanding level of pollution. These industries are arranged into the accompanying classes based on pollution index, which is as under-

Sr. No.	Category	Pollution of the Index score
1	Up to 20	White
2	21-40	Green
3	41-59	Orange
4	60 and above	Red

White class of entities incorporates those industrial areas which are for all intents and purposes non-contaminating, for example, Cotton and woollen hosiery making, Electric light (bulb) and CFL fabricating by collecting just, Solar power generation, wind power, and smaller than normal hydel power, and so on the white classification contains 36 industrial areas. For working White class of entities, there is no need of getting consent. No industry falling under Red class can be functional in any ensured region.

The arrangement of businesses is done to guarantee that the business is set up in a way that ecological targets are accomplished and consequently controlling the outflow of exchange effluents and other risky releases by the industries. The industrial area will embrace cleaner advancements coming about into the environment of less pollution.