Geurdiffusie

Geurdiffusie is the process by which odor molecules spread through air or other media and become perceptible to humans or animals. It encompasses diffusion and advection, as well as turbulent mixing. In physics, diffusion is described by Fick's laws; in the atmosphere, advection by wind and turbulence are often the dominant transport mechanisms. Molecular diffusion in air has relatively small coefficients (about 0.1 cm2/s for many gases), so over short distances diffusion alone is slow; over larger scales, turbulent diffusion rapidly spreads odors.

Odour concentration may be modeled using dispersion models. Gaussian plume models apply for simple, steady sources; CFD models simulate complex flows around obstacles. Measurement uses olfactometry to quantify odour concentration, reported in odour units (OU) per cubic metre (ou/m3). Odour perception is subjective, so several panel-based methods are used to derive robust assessments.

Geurdiffusie is relevant in environmental impact assessments, permitting, and nuisance management for industries such as agriculture (manure storage, slurry), wastewater treatment, food processing, and landfills. In many jurisdictions, regulatory frameworks require odor assessments and mitigation strategies, such as covering storages, local air treatment, or buffer zones.

Limitations: Odour diffusion depends on meteorological conditions; background odors; source strength; wind shear; temperature and humidity. Models provide estimates with uncertainties, and real-world results may differ due to complex interactions in the atmosphere and surrounding landscape.