Both methodologies share the same basic structure but present considerable differences regarding input data, assumptions and parameters (Reynolds and Broderick, 2000). The selection of the approach and the quality and consistency of the inventory depends almost entirely on the availability of the data and its degree of detail (Reynolds and Broderick, 2000; Tsilingiridis et al., 2002). It is futile to expect emission calculations to achieve results that are superior in accuracy to that of the original survey data (Sturm et al., 1996).