On the source inversion of fugitive surface layer releases. Part I. Model formulation and application to simple sources V. Sanf  elix, A. Escrig * , A. L  opez-Lilao, I. Celades, E. Monfort Instituto de Tecnología Cer amica-AICE, Universitat Jaume I, Campus Universitari Riu Sec, Avda. Vicent Sos Baynat, 12006 Castell o, Spain highlights  A dispersion model that incorporates the MonineObukhov theory is described.  The model explicitly accounts for plume meandering and wind shear effects.  The model is sufficiently flexible to realistically model fugitive PM sources.  Operation-specific PM 10 emission factors for fugitive sources are provided. article info Article history: Received 1 December 2014 Received in revised form 5 March 2015 Accepted 10 March 2015 Available online 11 March 2015 Keywords: Dispersion modelling Emission factor Fugitive emissions Particulate matter Atmospheric surface layer abstract Source inversion by dispersion modelling of fugitive particulate matter (PM) emissions entails consid- erable difficulty. Fugitive PM sources are rarely steady or point sources. They occur near the ground, where there are high vertical gradients of wind velocity and potential temperature. To resolve the source from the background concentrations, measurements need to be conducted very close to the source. In this study, a dispersion model was developed that consists of numerically solving the pollutant transport equation, while incorporating the MonineObukhov similarity theory. By using this numerical approach, in contrast to Gaussian dispersion models, wind shear effects and plume meandering were accounted for directly. A series of controlled experiments were conducted, in which the fugitive PM sources were parameterized as much as possible. The developed model was used to obtain operation-specific PM 10 emission factors (EFs). This is the first of two articles describing the model and the field campaigns in which it was applied to determine the EFs. Part I describes the mathematical model and its application to two relatively simple sources. © 2015 Elsevier Ltd. All rights reserved. 1. Introduction In industrial areas where dusty bulk solids are handled, partic- ulate matter (PM) emissions into the atmosphere from ducted and fugitive sources are a major environmental issue. Ducted emissions are released into the air through a duct (often an industrial stack). In contrast, fugitive emissions are pollutant releases that are not discharged into the air in a confined flow stream, but from a somewhat disperse area or volume (US EPA, 1995). Fugitive pollutant emissions have traditionally drawn little regulatory attention, despite their relative importance in industrial activities where they can account for much of the industry's par- ticulate emissions. Such activities include ceramics manufacture, cement and concrete production, quarrying, steel foundries, aggregate plants, harbour activities, and construction work. This situation can be aggravated in warm climates, where these activ- ities are often carried out in the open air and the moisture content of bulk solids tends to be relatively low (Monfort et al., 2011). The lack of attention to fugitive emissions may be partly due to the intrinsic difficulty in their measurement. Even though methods have been proposed for a straightforward quantification, such as the so-called profiling technique (Cowherd et al., 1974), objections have been raised over the accuracy of these methods (Venkatram, 2000). As suggested by Venkatram (2000) for emissions of PM less than 10 mm in aerodynamic size (PM 10 ) from paved roads, modelling the atmospheric dispersion of the pollutant to solve the inverse problem for determining the emission rate appears to be the most flexible and accurate technique. Source inversion by dispersion modelling of airborne pollutants * Corresponding author. E-mail address: aescrig@itc.uji.es (A. Escrig). Contents lists available at ScienceDirect Atmospheric Environment journal homepage: www.elsevier.com/locate/atmosenv http://dx.doi.org/10.1016/j.atmosenv.2015.03.024 1352-2310/© 2015 Elsevier Ltd. All rights reserved. Atmospheric Environment 109 (2015) 171e177