Air pollution can lead to plant damage and accumulation of pollutants in plants. Systematic investigations of such substance accumulations allow conclusions to be drawn about the extent of the effects of air pollution and possible risks for plants, animals and humans. The standard describes the use of curly kale as a bioindicator for assessing pollutant levels in home-grown food crops with reference to human consumption. Curly kale is particularly suitable as a bioindicator for persistent, organic pollutants, but also immission-related inputs of (heavy) metals can be recorded. The individual steps from the cultivation and exposure of curly kale to the sampling and processing of the plant samples to the evaluation of the determined pollutant contents in relation to human consumption are presented in the standard. Curly kale is representative for all leafy vegetables, such as spinach, chard, lettuce, rocket and lamb's lettuce. The standard is only applicable to non-commercial cultivation of food crops, for example in home gardens or allotment gardens.