Method Development to Assess the Ventilated and Nonventilated Sources of Indoor Dust Deposits, Applied in a Museum

A method was developed to analytically distinguish between the ventilated (v) and nonventilated (nv) fractions of water-soluble ions in deposits of particle indoors. The indicative method was based on low-cost passive outdoor and indoor sampling of the particle and ion deposits and NO₂ gas and analysis of the regression values and residuals of the correlations between these parameters. The method was applied to measurements in the Pieskowa Skała Castle Museum in Poland. A dominating source of “soil and building dust” was indicated all year round, probably partly from renovation works of the castle, with larger total infiltration in the winter–spring (W-S) but with a higher proportion of ventilation ingress in the summer–autumn (S-A). About 60%–80%, by mass, of the water-soluble ions in the soil and building dust were calcium and probably some magnesium bicarbonate (Ca(HCO₃)₂, Mg(HCO₃)₂) and about 10%–20% sulfates (SO₄⁻⁻) with calcium (Ca⁺⁺) and several other cations. The other main source of the ion deposits was indicated to be air pollution, with chloride (Cl⁻), sulfate (SO₄⁻⁻), and nitrate (NO₃⁻), from outdoor combustion sources, like traffic, residential heating, and industry. These were mainly v from outdoors in the colder parts of the year, but also to the more open locations in the S-A. A small source of nv sulfate (SO₄⁻⁻) was identified inside two showcases in the S-A. The study showed good enclosure protection of the museum objects against exposure to particle pollution, but also the need to avoid the trapping of particle pollution inside showcases or closed rooms. The identification of the probable different amounts and sources of v and nv ions in the castle aided preventive actions to reduce the pollution exposure.