scope:

This standard describes the range of use and practical steps of the method of the standardised grass exposure in order to determine and assess the accumulation of air pollutants as deposition-related changes (= effects).

The aim of deploying the method of the standardised grass exposure is to detect the transition of substances from atmosphere to vegetation using a substance-accumulating, standardised plant stand. This grass culture is a proxy for fodder but also for food such as leafy vegetables.

Humans and most animals in terrestrial ecosystems take up persistent air pollutants primarily with their food. Therefore, the method of the standardised grass exposure can also provide the base for assessing the risk of eating fodder or food cultivated outdoors.

The method applies to solid and gaseous substances deposited on plants, where they may accumulate on the plant surface or within the tissues. These substances include sulphur, chloride, fluoride and especially metals as well as low volatile organic and halo-organic compounds such as polycyclic aromatic hydrocarbons (PAH), polychlorinated biphenyls (PCB), polybrominated diphenyl ethers (PBDE), polychlorinated dibenzo dioxins (PCDD) and polychlorinated dibenzo furans (PCDF). The range of potential substances may be expanded according to the task at hand and the capabilities of conducting trace analyses and assessment.

The grass culture is exposed outdoors at different distances around emission sources and additionally in non-exposed sites (background sites). Thereby, requirements on plant material, exposure sites, etc. shall be observed (cf. Section 6). Deviation from the specifications can cause differences in growth and accumulation of air pollutants, which impedes comparability among measurement results as well as comparability with other studies and a correct assessment of measured values.

Potential areas of deployment are (according to VDI 3957 Part 1 and VDI 3957 Part 10):

• permit procedures related to the Immission Control Act and to environmental impact assessments,

• preservation of evidence related to the code for protection from pollution,

• monitoring of emission sources and performance control,

• assessment of local-scale emission dispersion,

• evidence of causation, e.g. related to environmental liability,

• air quality maintenance plans/strategies,

• long-term monitoring of ecological effects of atmospheric depositions,

• detection and assessment of local, regional and countrywide immission effects,

• assessment of risks for humans and/or animals via the food chain.

Fundamental information for assessing the concentration of substances and assessment values for inorganic elements in standardised grass cultures are presented in standard VDI 3857 Part 2.