scope:

For the assessment of the possible impact of a plant due to bioaerosols, knowledge of the background concentration is important. The measurement strategy described here is used for determining the background concentration of bioaerosols.

The effort described here for the determination of the background concentration is important in order to permit a sufficiently statistically sound determination in consideration of the various influencing factors. It is in principle possible to reduce the Besampling effort, but this results in a much higher uncertainty.

The task of measurement planning involves analysing a given measurement problem. This results in organisational requirements as well as those relating to measurement techniques, measurement strategy, evaluation, quality assurance, and reporting.

The requirements set out in this standard permit the planning of measurements to determine the background concentration of bioaerosols in such a way as to enable a given task to be processed with sufficient informative power and with justifiable effort. As a result, the obtained findings are sufficiently representative and as comparable as possible

Plant-affected bioaerosol concentrations can be determined with ambient measurements on the basis of the plume model (VDI 4251 Part 1). By simultaneously determining the plant-related background concentration (up- and downwind measurement), it is possible to then assess the determined concentrations by comparison.

For the planning of a plant, the bioaerosol concentrations can be determined with dispersion calculations in accordance with VDI 4251 Part 3. An assessment of bioaerosol concentrations at individual receptor points is then performed on the basis of the environmental health decision flow scheme (VDI 4250 Part 1) with reference to the assessment criteria of "background value", "attention value", or "limit of quantification". While the attention value and limit of quantification already exist for certain measurement parameters, representative measurements of background concentrations have to be carried out and marked with suitable statistical parameters in order to determine the background value.

The difficulty of determining the background concentration of the cumulative parameters "total fungal count" and "total bacterial count" is due to the natural fluctuation range in the concentrations. Depending, for instance, on the season or location, these can vary by several powers of ten. propriate evaluation of bioaerosol concentrations in the vicinity of planned plants