How are pollution-free, green and organic vegetables divided?

Vegetables are divided into three grades: pollution-free, green and organic. Among them, pollution-free means that low-toxic fertilizers and pesticides can be used in the process of vegetable planting, but the content of harmful substances should be controlled within the prescribed standards, that is, pesticide residues should not exceed the standard. Strictly speaking, pollution-free is only a basic requirement, and any vegetable must meet this requirement. This has become the current "green" standard. Green vegetables refer to vegetables that have been certified by the agricultural department and licensed to use the green food logo. Since 1996, the country has divided green vegetables into AA and A grades. Class A allows limited use of chemical synthetic substances, while Class AA stipulates that no harmful chemical synthetic substances can be used. Organic vegetables are synthetic substances such as pesticides, fertilizers, hormones, herbicides and synthetic pigments, which are absolutely prohibited during planting. Pollution-free and green vegetables are only allowed to be used in a limited way. Green vegetables are the product of the transition from pollution-free vegetables to organic vegetables.