Higher plants as indicators and accumulators of gaseous air pollution.

Some higher plant species or varieties are very sensitive to certain gaseous air pollutants, and the resulting effects show sometimes more or less specific, well-visible and measurable symptoms.On this basis several species and varieties of natural and cultivated plants have been selected to serve as biological indicators for the possible presence of certain air polluting substances. But these indicator plants may also be used for the quantitative determination of the effect intensities of the air pollutants involved.Besides, some plant species or varieties may accumulate certain components of air pollution, without changing these substances, in such a way that after accumulation in the plants these substances may be analyzed physicochemically (qualitatively and quantitatively).Definitions are proposed and examples are given of both indicator and accumulator plants. Also information is displayed on the methods for the use of plants as indicators and accumulators of air pollutants (standardized system of plant cultivation and exposure). Some applications of biomonitoring the effects of air pollution with plants are discussed and illustrated with data from The Netherlands.