Potential effects of particulate matter from combustion during services on human health and on works of art in medieval churches in Cyprus

Indoor and outdoor particulate matter (PM0.3–10) number concentrations were established in two medieval churches in Cyprus. In both churches incense was burnt occasionally during Mass. The highest indoor PM0.5–1 concentrations compared with outdoors (10.7 times higher) were observed in the church that burning of candles indoors was allowed. Peak indoor black carbon concentration was 6.8 μg m−3 in the instances that incense was burning and 13.4 μg m−3 in the instances that the candles were burning (outdoor levels ranged between 0.6 and 1.3 μg m−3). From the water soluble inorganic components determined in PM10, calcium prevailed in all samples indoors or outdoors, whilst high potassium concentration indoors were a clear marker of combustion. Indoor sources of PM were clearly identified and their emission strengths were estimated via modeling of the results. Indoor estimated PM0.3–10 mass concentrations exceeded air quality standards for human health protection and for the preservation of works of art.