Modeling of the aerosol infiltration characteristics in a cultural heritage building: The Baroque Library Hall in Prague

Three intensive campaigns in spring, summer and winter 2009 where conducted in the Baroque Library Hall in Prague, Czech Republic. The number concentration of particulate matter (PM) was measured online and simultaneously, both indoors and outdoors with an SMPS (0.014-0.7 μm) and an APS instrument (0.7-20 μm). A dynamic mass balance model was introduced taking account particle penetration from outdoors and indoor losses (deposition, ventilation). The model was used to determine deposition rate k and penetration efficiency P in 13 discrete size intervals. Model performance was evaluated using the coefficient of determination (R2) by selecting different pairs of k and P. No unique solution found, thus, averaged values of k and P from the best correlated pairs were used to estimate infiltration factor. Good agreement between infiltration factor and I/O ratio confirmed that modeled k and P were well-estimated. The deposition rate was found to depend strongly on particle size with higher rates for ultrafine and coarse particles. Penetration efficiency, on the other hand, was not clearly related with particle size. The infiltration factor varied substantially with particle size with less effective removal for accumulation fraction (0.1-0.7 μm). Higher infiltration factor for ultrafine particles, compared to coarse particles, indicates that enrichment of the library at this size is caused by penetration from outdoors. On the other hand, human presence during visiting hours found to contribute significantly to coarse particles by increasing the indoor number concentration by a factor of 3, 3.2 and 2 during spring, summer and winter respectively.