If the balcony is close to the road and other areas with turbid air, the vegetables planted on the balcony will be affected by the air of many pollutants such as automobile exhaust and dust powder, which will lead to unhealthy dishes.

Because the vegetables usually planted on the balcony are mostly inferior containers, and this container will contain some chemicals and toxic substances, which may enter the vegetables. In addition, the soil planted may be dug from ruins, flower beds and other places.

It is likely to contain toxic substances such as municipal solid waste and heavy metal waste residues, and it will also pollute balcony vegetables.