## 1 Introduction  
Like many other industrial activities with odor emissions, bitumen-related production sites, like bituminous conglomerate (BC) and bituminous waterproofing membrane plants, are facing increasing difficulties coexisting with residents in proximity of production facilities due to odor emissions. In fact, odor pollution is increasingly perceived as both a health impact [1; 2; 3; 4], due to its potential toxic effects, and as an impact on subjective well-being of bitumen-related production sites by residents living in areas exposed to environmental odors. This exposure, from a physiological point of view, has acute health effects, such as nausea, headache, eye and throat irritation [5], and also causes neurogenic inflammation caused by stimuli of chemical irritant receptors in the upper airways and skin [6]. However, there are also psychological effects in people due to stress. Exposure to environmental stimuli, such as odors, in fact, cause an immediate release of catecholamines, which evoke the first signs of stress response, glucocorticoid hormones that are responsible for the effects [7] of stress adaptation, and they also have negative psychological and behavioral consequences [8]. Production plants use different production technologies to pursue, for new plants, objectives that ensure environmental protection, both from an energy point of view, for example with the use of materials that allow production at lower temperatures (warm mix asphalt), and from the point of view of odor emissions, with more confined plants to control fugitive emissions. The emission of odors occurs, in fact, not only through the stack, where the fumes coming from the hot mixing of a bituminous binder with inert materials are emitted, but also from uncontrolled diffuse emissions, due to the storage and handling operations of bitumen at high temperatures. Emissions may contain particulate matter, hydrocarbons (VOCs), and hydrogen sulfide (H\({}_{2}\)S), and the levels of emitted pollutants depend on the quality of the raw bitumen material used, the production site, crude oil being used as raw material, the handling and storage of the bitumen, and the inert material, the amount of reclaimed asphalt pavement in the mix and the mixing process used, for example [9]. The different formations of VOCs, including odorous gases, depend on various parameters, such as asphalt temperature, asphalt oxidation and air humidity, and large variations are observed under different operating parameters [10]. Using an electronic nose, different odor patterns have been identified in bitumen produced with crude oils of different origins [11] and in chemical additives and wax modifiers [12], but no data are available about true sensory evaluation (olfactometry). Additionally, to the best of our knowledge, while few data are available on specific odorant's stack emissions, such as hydrogen sulfide [13], there is only one published report on bituminous conglomerate plants' stack emissions odors [14]. In Italy, guidelines are available on the characterization and authorization of gaseous emissions into the atmosphere from limited specific plants considering odor impacts, but there are no specific guidelines for BC plants [14], which do have odor emissions that enter the environment. Currently, authorization for emissions of BC production plants are generally limited to pollutants in stack emissions, such as particulate matter (PM), total hydrocarbons (THC), and polycyclic aromatic hydrocarbons (PAH) and do not consider odor emissions. The first step to being able to create guidelines is the need to have data on emissions from industry at a national level, with the technology that is currently in use. This is fundamental in order to have benchmarks on which to base a dialogue with interested parties. In this work we present the data available from several monitoring campaigns focused on odor emissions from hot mix asphalt (HMA) and bituminous waterproofing membrane plants, which will be used to quantitatively describe this specific industry sector.