**7. Conclusion**

that radon concentration is to be determined, irrespective of the priority area, in

The church under discussion is included in the Historical Monuments List, under the code LMI: MM-II-m-A-04569, and this inclusion was approved by the Directorate of Historical Monuments from the Department of Worship, no. 14301-1514 from the 5th of September 1967. The site is a public access building, visited by tourists and religious followers. In the summer of 2019, a group of 50 pilgrims led by a monk, attended the Holy Mass at the church on the hill. In the last few years, the church has been visited by a high number of visitors attracted by this part of country, rich in tradition and culture. Under these circumstances, we considered it necessary to evaluate the natural radioactivity, by radon measurements, of the

Active radon measurements carried out during the two separates campaigns yielded indoor radon activity concentrations ranging from 29 to 364 Bq m<sup>3</sup>

the first campaign, one of the windows could not be closed properly; this allowed a high air exchange rate that led to the dilution of indoor radon to an average value of

restored. The average value of 166 Bq m<sup>3</sup> was recorded during the second monitoring campaign. The indoor radon time series for the two seasons [35] monitored

. By the time the second campaign took place, the faulty window was

At the time of the second campaign, passive radon detectors were installed along the active monitoring system. Indoor passive radon measurements were performed by using CR-39 track detectors exposed for 1 month, in all three rooms of the wooden church (**Figure 15**), according to the NRPB Measurement Protocol [36]. Following the laboratory analyzes performed at the Constantin Cosma Radon Laboratory of Babeș-Bolyai University, an average concentration of 107 Bq m<sup>3</sup> was obtained for the monitored period. Taking into consideration the seasonal correction factors implemented through national regulations, the annual indoor radon activity concentration for the investigated public building was calculated to be 140 Bq m<sup>3</sup>

. During

,

buildings with public access [34].

46 Bq m<sup>3</sup>

*Heritage*

**Figure 15.** *CR-39 detector.*

**214**

"Archangels Mihail and Gavril" wooden church.

were represented in **Figures 7** and **10**.

In the short-term analysis, the results of 30 days of continuous monitoring showed that environmental climate changes can have an influence on the interior conservation status of the studied church.

Future work should focus on the implementation of long-term measurements, deepening these techniques as well as performing chemical and biological analyzes at the mural painting level.

Taking into account these aspects, a short-term recommendation would be to install a portable air dehumidifier with a setting function allowing the relative humidity of the air to be brought in between 50 and 60%.

## **Acknowledgements**

This work was supported by a grant of the Romanian Minister of Research and Innovation, CCCDI–UEFISCDI, project number PN-III-P1-1.2-PCCDI-2017-0476/ 51-PCCDI/2018, within PNCDI III, ACRONIM: ARHEOCONS.
