Air Quality ModellingModelling assessment of odours
The assessment of odour impact is an increasingly relevant element in environmental procedures, since odorous emissions generated by industrial activities, agri-food plants, waste treatment facilities or infrastructure can affect the quality of life of communities and limit land usability. TerrAria addresses odour impact through a modelling approach that makes it possible to estimate odour dispersion at local scale, assess predicted concentrations and verify the potential occurrence of odour nuisance at sensitive receptors. Models such as CALPUFF (non-steady-state Lagrangian model), applied with detailed meteorological data, make it possible to describe odour propagation under complex orographic and atmospheric conditions, translating odorous emissions into spatial and temporal scenarios useful for technical assessments and authorisation procedures.
From a regulatory point of view, the main reference is Article 272-bis of Legislative Decree 152/2006, introduced by Legislative Decree 183/2017, which allows the competent authorities to prescribe specific measures to contain odorous emissions: concentration limits, maximum flow rates expressed in odour units, containment plans and location criteria according to the presence of exposed receptors. The objective is to prevent or mitigate persistent odour nuisance situations and ensure that production activities are compatible with urban planning instruments and the needs of the population.
The measurement of odour impact is generally based on odour concentration expressed in OUe/m³ (European odour units), according to UNI EN 13725, which defines sampling and analysis methodologies through dynamic olfactometry. In the absence of a single national regulation on odour nuisance, several regions – including Lombardy, Piedmont and Apulia – have adopted guidelines that introduce reference values, often based on the annual 98th percentile of hourly concentrations (equivalent to 2% of the hours of the year). The Lombardy Region Guidelines on odours also specify the use of a coefficient equal to 2.3 (peak-to-mean) to obtain peak hourly concentrations from average hourly concentrations. Once concentrations have been estimated through the modelling approach, TerrAria processes the related odour dispersion maps, assessing compliance with the 98th percentile reference values and identifying any critical situations for sensitive receptors.
By integrating modelling, UNI standards and regional references, TerrAria provides a complete assessment of odour impact, useful for planning, authorisations and defining effective measures to contain odorous emissions and reduce odour nuisance.
