Imeni. J. Eminm. Mal Chem.. Voi. M. pi). 71-81 O Wfi ORA (Overseas Publishers Association) Rcprints avallatile dirccrly from tlie publislier Amsterdam B.V. Publisind in The Nctherlands Phou>copyingi>ciTOItedlixlicen5i--only under license by Gorclon and BreachSuicnce Publishcts SA Prinlcd in Malaysia CHARACTERIZATION OF INDOOR AIR QUALITY IN THE CHURCH OF SAN LUIGI DEI FRANCESI, ROME, ITALY F. DE SANTIS, I. ALLEGRIMI, M. C. FAZIO and D. PASELLA CNR—Istituto Inquinamento Atmosferico, A. d. R. Roma, Vìa Salaria Km 29,300, CP IO, 00016 Monterotondo Scalo, Roma, Italy (Receivcd, 20 Oaoher 1995; Infutatfarm, 5 March 1996) Simullaneous indoor and outdoor samples collecied in thè Church of Sun Luigi dei Francesi were analyzed for nitrous acid, sulphur dioxide, nìlrogen oxides and ammonia in thè gas phase and for ammonium, sulphate, and jiitrate ions in tlie partjculate matter. Indoor levels of nilrogen oxide, nitrous aeìti and ammonia were found to largely exceed those outdoors. For NO, and S02 lower indoor levols were always measurcd, while for nitrale and sulphate, thè indoor/outdoor ratios ranged Tram 0.5 io 3.5. Thcse rcsults show Ihat indoor production of nitrous acid could result from heterogeneous reactions indoors, on thè walls and exposed surfaces. Furtherrnore, they demonstrate that non-reactive species such as nitrogen oxide and particles penetrate indoors, where they remain segregatcd and are very slowly depleted, due io their small deposition vdochies. KEY WORDS: Indoor pollution, diffusion techniques, m'trous acìd. nìtrìc acid INTRODUCTION A factor \vhich ìs often overlooked in thè confmed environinent of a builtlìng intended for storing or displaymg amvorks or manufacts of cultural or artìstìc value, is thè role of atmospheric pollutants which can be transferred indoors. In this regard, it is knovvn that an important process which contributes to thè damage of artworks Ìs thè dry deposition of acidìc specìes1"3 and ozone4, Acidity in thè air is essentially caused by criteria pollutants, such as sulphur and nitrogen oxides, which are emitted into thè atmosphere by sources related to industry, transportati on and heating. These species are transformed in thè aimosphere, through compiex reaction pathways, into secondar/ pollutants, in particular into gaseous nitric and nitrous acids and into acidic sulphates in particulate matter. A recent study of thè air quality in one of thè most important Italian Museums—thè Uffìzi Gallery, Florence—has demonstrated thè presence of consistent levels of HNO3 and other aggressive species such as SO2 and O/ which have been ascribed to penetration from outdoors. In thè sanie study, hìgh levels of indoor MONO, greatly exceeding those outdoors, have also been measured. Although thè exact mechanism of formarion of this species is stili not completely understood, there are sound indications6'11 that ìts presence indoors could be Indicative of a major hazard to thè artworks in consideratìon of thè fact that HONG production is coupled with thè heterogeneous formatìon of HNO3 on surfaces- most likely including artworks-accordìng to thè following reaction: 2 NO2 + H,O -> MONO + HNO3 (1) 7!