For dry deposition velocity of submicron particles, there exists in the scientific literature an ambiguity in that laboratory measurements largely support well established models, and yields quite small deposition velocities (e.g. Slinn, 1983), while some field data indicates larger deposition rates (Sievering, 1981 and Hicks et al, 1986). The deposition models all indicate, that the limiting factor for the deposition rate is the transport across the thin laminar layer close to the surface, with a depth less than typical 100 um. It has been argued that a reason for the difference between field and laboratory data derives from that such thin layers are often disrupted in the natural environment, while they can be well established in the laboratory studies. However, the odds against measuring correctly the often extremely small deposition rates over a natural water surface is very large, with the methods presently available, see e.g. Slinn (1983).