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Biomonitoring - monitoring and assessing the effects of air pollutants

Sensitive organisms, e.g. selected and screened plant species, can be used to assess and demonstrate the effects of air pollutants directly on the spot. Therefore, Biomonitoring may be considered one of the most important tools in effect-related environmental monitoring.
Compared to technical measurements, which generally detect single pollutant species with high accuracy and high resolution in time, biomonitoring methods can integrate over all environmental factors, which act upon an organism, and over longer periods of time (e.g. weeks or months):
Not a single pollutant compound, but the combination of all acting pollutants including environmental factors like, e.g. the climate, are determining for potential effects on organisms.
Biomonitoring methods can provide information on pollutant effects in a quantitative way.

Injured leaf tips of Gladiolus indicate the effects of fluoride air pollution. The length of the necrotic (=dead) leaf tip is proportional to the pollution load. (VDI Guideline 3957/14).

Results of biomonitoring are relevant, because:
they consider the critical criterion: the effect of pollution stress. Because prevention of harmful effects is the ultimate goal in environmental protection rather than formal compliance with standards and limits.
they register pollution impact in a time-integrating manner.
Technical measurements normally provide only a 'snapshot' of the concentration of a particular pollutant - except they are operating continuously, which is costly and therefore not applicable in extensive and dense monitoring networks. In contrast, biomonitoring organisms are registering the pollution impact over severals weeks - during day and night, and they don't take vacations.
they are inexpensive and therefore
allow for high spatial resolution of networks

they provide a basis to assess the risk for vegetation and - by pollutant transfer through food chains - for man and animals
they provide a measure to assess the result and success of air pollution abatement strategies and can be employed publicly with broad acceptance.

Therefore, biomonitoring complements and supplements chemical monitoring by providing results which are meaningful and which can be easily explained even to laymen. It is particularly suitable for Air Quality Assessment.

Various biomonitoring procedures have been successfully applied in air pollution monitoring for many years.
Most of these methods are regulated by VDI-Guidelines (VDI = Association of German Engineers). Thus, standardisation is ensured on a high level and consistency and comparability of results is warranted.