Abstract
Sampling is a key step in environmental analysis. For odorous atmospheres, mostly sample bags are used to carry out olfactometric or chemical analyses. Despite the description in some protocols, like VDI-3880 (2011) of how to sample area sources, it was demonstrated by the last version of European standard (EN-13725:2022) that it is impossible to fix a consensus about the sampling method for such emission sources. Studies showed that the type of device (Flux Chamber FC or Wind Tunnel WT) is highly influencing the sampling and thus also the expected result. This means that the real emission is hard to predict with these methods and the resulting value is probably either underestimated or overestimated. Comparison of results between sampling labs is a real challenge. The result of sampling with FC or WT is always linked to conditions and gives relative values, that are only comparable with the same device used in the same conditions for the same type of source. The uncertainty of FC and WT appears to be way too high. Moreover, these methods present lots of drawbacks: difficulty to place devices on a surface (without leaks on a solid surface or with acceptable floatability on a liquid source); difficulty for operators to place and move the device in different locations; necessity to have odourless flux air for inlet in the device, limitation in surface that is effectively sampled… So, without a clear method for sampling, without consensus about values obtained using FC and WT, the question of a paradigm shift using aerial drones is clearly posed to improve assessment of real emission rates from large area sources and their impact after dispersion.
This paper deals with all advantages and drawbacks of these approaches and illustrates that the shift is probably a significant step forward. First of all, operators can stay away from the emission source, which is a real improvement for safety conditions, without risk of falls or drowning and with less exposition to odorous pollutants. Secondly, the possibility in terms of sample numbers is increased with the easiness to change the sampling point and, it also gives a stronger flexibility to average emission from different points. Third, when using this method, we can measure the real windflow and thus the result is not dependent on the choice of the windspeed.
