## 4 Discussion  
The results of the monitoring highlight some issues for the assessment of microclimatic parameters and IAQ pollution. With respect to the microclimatic parameters (Figure 6), the measured values compared with the recommended ranges showed acceptable values for air temperature in the majority of the rooms--in some of them the values were only slightly over the limit value. For relative humidity, the values were above the limits when the museum was closed to the public in Room 10, Room 35, and Room 41. For the temperature values, the environment with the highest values (over 26 \({}^{\circ}\)C), which went beyond the conservation levels of the paintings and the comfort of people, was the Verone II floor, which had no HVAC systems. By comparison between data collected in the rooms with the museum closed and when open to the public, it was observed that when the museum was closed, the temperature and relative humidity values were often outside the optimal ranges. In particular, when the museum was closed, the temperature had lower values and the relative humidity higher values, even reaching 70% in Room 10 and Room 41. These data suggest that when the museum was closed, with climatic conditions that were not critical for a lack of sensible heat due to the occupants, the temperature was lower due to the absence of the public; under these conditions, the HVAC system was not able to control the relative humidity as it was not working under standard operating conditions. The fluctuations in the above-mentioned parameters must, therefore, be carefully assessed so that they do not cause damage to the artefacts of the museum. To guarantee and maintain optimal microclimatic conditions for the correct conservation of the objects displayed, variation in the temperature and relative humidity values must be carefully monitored, in particular, where paintings on wood are exposed. The best conditions are those that address, at the same time, air conditioning requirements, energy saving needs and the architectural constraints of the museum operating in an historic ancient building. For carbon dioxide, the rising values sampled in some museum rooms can be related to the presence of visitors and staff, to outdoor pollution and to the non-optimal positioning of the air inlet and outlet grids of the HVAC system. As shown in Figure 7, the threshold value was exceeded in the most crowded rooms, Room 2 and Room 10, and at the entrance of the museum, where there was always a queue. During opening hours, the average values in Room 2 reached 1516 ppm, in Room 10 1442 ppm, while in the Entrance, an environment without air exchange and with a greater concentration of public visitors, CO\({}_{2}\) average values of 2183 ppm were measured, with peaks of 2404 ppm. In the Verone II floor, also without mechanical ventilation, much lower CO\({}_{2}\) average values were recorded, equal to 1055 ppm, probably due to the lower concentration of visitors. The comparison between the measured values of the CO\({}_{2}\) concentration in the presence of visitors (average concentration in Room 10, Room 35, and Room 41 equal to about 1049 ppm) and when the museum was closed (average concentration in Room 10, Room 35, and Room 41 equal to about 540 ppm) made it possible to evaluate the influence of the presence of the public, which was associated with an approximate doubling of the background concentration of CO\({}_{2}\) in rooms with mechanical ventilation. Figure 10 shows the trend in CO\({}_{2}\) concentration measured by the continuous monitoring system owned by the museum and present only in Room 160 from 3 to 6 June 2019; these data are in line with those monitored during the spot campaign (with a difference of about 5%). The CO\({}_{2}\) minimum value measured in Room 160 in this period was 530 ppm (museum closed) while the maximum value was 1040 ppm (museum open).