## 1 Introduction  
Atmospheric pollution is a relevant task in life sciences and, in particular, inorganic fraction characterization is considered an important issue in this field. For many years, researchers have focused their attention on the particulate matter fraction below 10 \(\upmu\)m: nowadays, general attention has been focused on PM\({}_{2.5}\) (i.e., particles below 2.5 \(\upmu\)m) and PM\({}_{1}\) (below 1 \(\upmu\)m). In previous papers [1; 2], the authors investigated how the elements were distributed between two sub-fractions of PM\({}_{10}\) (i.e., _coarse_ (airborne fraction between 10 and 2.5 \(\upmu\)m, PM\({}_{10-2.5}\)) and _fine_ (airborne fraction below 2.5 \(\upmu\)m, PM\({}_{2.5}\)) fraction). This approach was followed to study the element distribution in urban particulate matter for a better knowledge of both the inorganic content, especially, the elements never determined as well as the contribution of anthropogenic sources [3; 4; 5; 6; 7]. Briefly, few elements such as Fe and Sb showed an even distribution between the two fractions whereas some of them (i.e., Au, Ba, Ce, Cr, Cs, Hf, La, Mo, Nd, Sb, Sc, Sm, Th and Yb) showed levels more elevated in the coarse fraction than in the fine fraction; on the other hand, As, Br Ni, Rb, Se, W, and Zn displayed an opposite behavior. Finally, Co, Hg, and Zn (three anthropogenic elements) exhibited no predominant distribution between the two granulometric masses. Furthermore, in other previous papers [8; 9], the authors only demonstrated the importance of PM\({}_{1}\) determination in areas with high anthropogenic sources (e.g., industrial emissions, combustion processes): this fraction represents almost 60% of the total mass of PM\({}_{10}\) and more than 80% of the PM\({}_{2.5}\) in terms of granulometric fraction.  
One of the most controversial topics in the environmental field with regard to the issue related to municipal solid waste (MSW) incination is plants that produce energy by waste (waste-to-energy) [10]. The debate over incinerators typically involves business interests (representing both waste generators and incinerator firms) [11], government regulators [12; 13], environmental activists [14], and local citizens [15], who must weigh the economic appeal of local industrial activity with their concerns over health and environmental risk [16; 17; 18; 19; 20]. The incination is a key process in the treatment of hazardous wastes [21; 22; 23]: it has a number of outputs such as the ash and the emissions to the atmosphere of flue gas [24; 25]. Before the cleaning system (e.g., filters, scrubbers, baghouse filters), the flue gases may contain particulate matter, heavy metals, dioxins, furans, sulfur dioxide, and hydrochloric acid. If plants have adequate flue gas cleaning, the pollution components to stack emissions may be significantly reduced [26; 27]. For instance, fine particles can be efficiently removed from the flue gases with baghouse filters. A Danish study showed that, even if about 40% of wastes were incinated in plants with no baghouse filters, incinerators were only responsible for approximately 0.3% of the total domestic emissions of PM\({}_{2.5}\) to the atmosphere in 2006 [28; 29].  
This paper would like to verify the considerations about the cleaning systems related to the inorganic fraction. Starting from the emission sources, sampling campaigns were performed outside the plant to understand the inorganic fraction behavior. Actually, the main question regards if the element accumulation in granulometric fractions is similar or whether there are behavior dissimilarities. Among the different analytical techniques available for the analysis, the instrumental neutron activation analysis (INAA), a nuclear analytical method, is still the main informative approach for investigating the sample without any chemical-physical treatment [30; 31; 32].