Cultural heritage preservation: study of indoor air quality conditions by newly developed devices

For the preservation of cultural heritage items, in particular those based on very sensitive materials such as paper or parchment, one of the determining factors is the control of the indoor environmental factors, such as microclimatic conditions and concentrations of pollutants. However, in this analysis, it is also not possible to ignore the outdoor environmental factors: atmospheric conditions, daytime, seasonal and annual excursions, as well as the orientation of the storage or exhibition rooms. To promote preservation, some parameters must be kept within certain values. Temperature (T) and relative humidity (RH) may prove to be the most critical threats to book collections, composed of highly hygroscopic organic elements (paper, leather, parchment, etc.). In uncontrolled microclimatic conditions, they contribute to long-term deterioration, resulting in mechanical damage and mold growth. Furthermore, even in the presence of moderate infiltration of outdoor factors, indoor environments can contain high levels of pollutants, such as SO2, NOx, O3, etc., which also cause the deterioration such as embrittlement and discoloration of the paper, as well as the weakening or powdering of leather book covers. A fundamental and primary condition is thus the stability of the thermohygrometric values (T and RH). These indoor environmental factors are detected instrumentally with various devices. In this regard, one of the most common problems faced by conservators of archives, libraries and museums is that of identifying, among the available systems, a solution that allows monitoring the parameters in an effective and organic way, but at the same time simple and low-cost. This would also allow them to manage resources and thus replicate the detections in the different environments intended for the preservation. To meet this need, this thesis describes how a system based on low-cost sensors was assembled, connected to inexpensive Arduino boards, suitably programmed and managed by a PC. In particular, two types of devices were assembled: one for microclimatic control, MC-MoDe unit, and one for indoor air quality control, IAQ-MoDe unit. These devices have been applied in three different conservation institutes: different for their location in the city of Rome, but above all for their characteristics of the buildings. The library of the Pontifical Lateran University and its storage rooms in the underground floors; the monumental hall of the Bibliotheca Angelica, large in size and surrounded by a high wooden shelving that preserves the 100.000 ancient volumes; the reading room of the archive of the Institute for the History of the Italian Risorgimento, which is located 70 meters above the street level, at the top of the National Monument to Vittorio Emanuele II (or Vittoriano). The monitoring was carried out with measurement campaigns for the detection of microclimatic parameters and pollutants. These made it possible to characterize the environments intended for preservation. A spatial control was carried out, thus creating isoline map able to represent the microclimatic situation of the environment. Together with this, a monitoring over the time, positioning the sensors in selected points of the investigated room and collecting the data for several consecutive days, 24 hours a day, thus obtaining typical trends of the monitored parameters. The system proved to be easy to apply and, at the same time, did not affect the daily routines of the staff and users of the institutions involved, who were able to access the rooms even during the measurement campaigns. Furthermore, from the results obtained and discussed in this thesis, it turned out to be an effective, versatile and low-cost system, mainly using an open source technology, but above all valid for planning and managing the preservation of paper and parchment based cultural heritage.