5. Current status of biomonitoring

It is interesting to note that, in Europe, apart from accidents or specific polluted areas, pollution levels in both air and water are now relatively low. As a result, the use of bioindicator plants is becoming increasingly problematic. Indeed, in the case of low levels of pollution, the physiological disturbances induced by pollutants (particularly in terms of oxidative stress) are of the same order of magnitude as those induced by the environment (day-night alternation, for example) or by genetic variability.

However, in the air, there are still levels of a few pollutants in Europe that are high enough to be studied using bioindicator plants. These particular pollutants are essentially ozone O ₃ , nitrogen oxides NO _x and sulfur dioxide SO _2...