Due to the rapidly increasing industrialization after the second world war in some areas in the Netherlands, damage caused by air pollution occurred. Some gladiolus varieties are particularly susceptible while others did not show any symptoms. Near Pernis fruit trees were damaged. Some pear varieties showed irregular black margins along the leaves and finally all leaves blackened entirely and dropped. Need for further investigation is stressed. Some foreign literature is cited and a description of the author's experiences in this field during a visit through USA is given. Symptoms caused by SO/sub 2/, HF, oxidized unsaturated hydrocarbons and growth substances (2,4-D) are described and the methods in use are discussed including some for determining the chemical constituents in air pollutants responsible for damage in plants.