## 3 Results and Discussion
### Microbiological Air Pollution, Moisture Content of Woodent Walls and Air Humidity
It relates to the value of the permissible total concentration of fungi and bacteria in the air of residential, working, and public spaces at a certain level. According to the Expert Panel on Biological Agents' proposal, the permissible concentration of mesophilic bacteria and mold in the air of residential and public spaces is 5000 cfu/m\({}^{3}\). On the other hand, in archives, museums, museum warehouses, and historic preservation studios, the Expert Panel on Biological Agents recommends as safe for humans a microbiological contamination level of 2500 cfu/m\({}^{3}\) (total fungi and bacteria), while a safe level for museum pieces is 150 cfu/m\({}^{3}\)[21]. Among the mold species found were the strongly cellulolytic species _Trichoderma viride_, _Cladosporium herbarum_, and _Alternaria alternata_ but also those whose food can be paint binders: _Aureohosidium_ sp. and _Penicillium_ sp. Molds can also colonize and damage the interior design of historic buildings. The changes caused by these microorganisms to paintings, polychromes and gilding on wood, etc., are related to their life processes and concern the following mechanisms: enzymatic activity related primarily to the processes of nutrition and respiration, the release of various metabolic products into the environment that are harmful to historic buildings, and the disfigurement and masking of surfaces [22]. Molds are also indicators of excessive humidity in buildings. In the case of temperate climates, such indicators are _Alternaria alternata_, _Trichoderma viride_, _Acermonium_ sp. and _Mucor_ sp. found in the naive of the church, developing at Rh > 90% Rh, as well as _Cladosporium herbarum_, _Aureohosidium_ sp. developing at Rh 80-90% [23]. The numerous occurrences of these species may indicate that during periods when the church is unused, the relative humidity of the air may increase significantly. An essential factor in maintaining the longevity of structures is knowing the environmental conditions under which fungal infestation can occur. During the inspection of the church, the observed dampness was caused primarily by the discontinuity of the horizontal damp proofing of the building walls, lack of vertical damp proofing of foundations, lack of moisture insulation of floors, poor soil and water conditions of the object's foundation, capillary action of moisture from the ground through foundation walls, flooding of exterior walls by rainwater entering through leaks and poor profiling of the rainwater drainage system from the church building. Moreover, lack of adequate ventilation of the side porches of the entrance area and areas where the walls are duplicated and form an enclosed space (this applies to the walls at the junction of the side chapel, porch and have on the south side) and the effect of rainwater (so-called splash water) on the exterior walls and foundations were also noted. Morphological structures of the fungus _S. lacrymans_--considered to be one the most severe destructors of wood in buildings [24]--were found on the wooden structural elements and their interior located in the narrow and wide nave, the Chapel of St. Francis and its vestibule, and the porch under the tower (on the north and south sides). The church has been in use for more than 480 years. It has been expanded over the years, with the last remodeling performed in 1932. After 1932, St. Catherine's Church was no longer expanded; only ongoing renovation works took place, involving the replacement of damaged wooden elements, wall reinforcement, roof renovation, and site drainage. Based on an analysis of archival photos from the early 20 th century, it is clear how the environment around the site has changed over the past 100-plus years. Unfortunately, these changes were detrimental to the church, as they blocked the natural drainage of rainwater away from the building and exacerbated the degradation processes in essentially all the wooden elements in the ground zone. The renovation and modernization work performed removed the effects without eliminating the cause.