Design and testing of a controlled release antimicrobial system for fungal and bacterial suppression in indoor heritage environments

Airborne microbial contamination in indoor heritage spaces is a significant issue that needs a solution, as microbial deposition on art surfaces can cause bi-odeterioration. Therefore, it would be beneficial to reduce the microorganisms present in the air by introducing an air-cleaning system. One of the first attempts in this direction was proposed by Diaz-Alonso et al. [1] with the application of an active air purification system based on cold diffusion of tea tree essential oil, which was applied in a small space of the Los Santos Juanes Church of Valencia in 2021. In our work, tea tree essential oil has been encapsulated inside the pores of mesoporous silica particles to elongate the activity period of the oil and en-hance its performance. It is designed to be a part of a passive-release air cleaning system. This innovative air cleaning system has been tested in test rooms and compared with the free oil system. The complete air monitoring control (temper-ature, relative humidity, microbial assay, and particulate matter) performed in these rooms showed that the essential oil encapsulated in the microparticles, as passive release system, keeps its biocidal activity for a longer time than the free EO, both towards bacteria and fungi.