CHARACTERISTICS OF AIRBORNE PARTICLES INSIDE SOUTHERN CALIFORNIA MUSEUMS

The concentrations and chemical composition of suspended particulate m atter were measured in both the fine and total size modes inside and o utside five southern California museums over summer and winter periods . The seasonally averaged indoor/outdoor ratios for particulate matter mass concentrations ranged from 0.16 to 0.96 for fine particles and f rom 0.06 to 0.53 for coarse particles, with the lower values observed for buildings with sophisticated ventilation systems which include fil ters for particulate matter removal. Museums with deliberate particle filtration systems showed indoor fine particle concentrations generall y averaging less than 10 mug m-3. One museum with no environmental con trol system showed indoor fine particle concentrations averaging nearl y 60 mug m-3 in winter and coarse particle concentrations in the 30-40 mug m-3 range. Analyses of indoor vs outdoor concentrations of major chemical species indicated that indoor sources of organic matter may e xist at all sites, but that none of the other measured species appear to have major indoor sources at the museums studied. Significant fract ions of the dark-colored fine elemental (black) carbon and soil dust p articles present in outdoor air are able to penetrate to the indoor at mosphere of the museums studied, and may constitute a soiling hazard t o works of art displayed in museums.