# Sustainability in Italian Ceramic Tile Production: Evaluation of the Environmental Impact
## 2 Materials and Methods
### Environmental Indicators  
Data on pollution have been collected among Italian producers of ceramic tiles over a period of thirty years, starting from 1988 [36]. The data collection and relevant elaborations have been carried out by Centro Ceramico, in collaboration with the industry association Confindustria Ceramica and Emilia-Romagna region (Italy). The data were collected by 90 ceramic tile factories located in Emilia Romagna region, representing a very complete picture of the ceramic tile sector in Italy. The data have been processed in order to provide a great number of environmental indicators representing pollutants at the gaseous emissions. The constant update of these indicators during the years has allowed for tracking the trend of the sources responsible for the environmental impact of ceramic tiles production and has granted a portrait of the efforts made for the improvement of the sustainability in this industrial sector. For the analysis carried out, the ceramic tile production process has been classified into 3 different classes:  
* class 1: complete production cycle (as reported in Figure 2);
* class 2: complete production cycle + production of spray dried powder for other companies;
* class 3: partial production cycle involving only the steps from pressing and without considering spray-dried powders production. Companies belonging to class 1 involve all the steps reported in Figure 2, from raw materials storage to the packaging of finished products. The extraction of raw materials is not included as they are mostly imported and managed by raw materials companies. Companies belonging to class 3, with a partial production cycle, are usually smaller than companies belonging to class 2. To highlight the environmental impact of the tiles production, two important environmental indicators have been considered:  
* EF\({}_{\text{i}}\) [mg/m\({}^{2}\)] or [g/m\({}^{2}\)]: emission factor of the \"i-th\" pollutant. It indicates the amount of pollutant released per square meter of tile produced. * R\({}_{\text{i}}\) [%]: recycling ratio for the \"i-th\" material. It indicates the ratio of water or solid waste recycled within the production plant. The environmental parameters reported are considered as performance indicators. In this way, each contribution (expressed as emission factor) to the environmental impact is independent to the specific productive dimensions of each ceramic tiles plant. The emission factors have been expressed based on the mass flow for each pollutant (kg/year) and the effective tiles production per each year (m\({}^{2}\)/year). In particular, the mass flow data supplied by each company for any specific pollutant is the sum of the mass flows of that specific pollutant over all the emission points on the production site, according to the annual flow and working hours of each plant. This information has been provided by each production plant from the current Integrated Pollution and Prevention Control (IPPC) directives and in line with each specific Integrated Environmental Authorization (AIA) document [37]. The AIA document is an authorization released to factories by the competent Italian authorities on the basis of factory production capacities (the threshold value for ceramic plants amounts to 75 ton per day). In addition, AIA documents regulate the compliance to the IPPC directive at regional or provincial level and they act in a more severe manner by applying lower limit values for each pollutant. All the data of total mass flows and recycling ratios are supplied by each company without relevant uncertainty. In this regard, the authors consider that it is not possible to associate uncertainty to the calculated environmental indicators. Additionally, the surveyed data are comprehensive of the different production specificities of each company and, for this reason, the values of the above-mentioned indicators should be considered as truly representative of the environmental impact of the Italian ceramic district.