CHARACTERIZATION OF INDOOR AIR-QUALITY IN THE CHURCH OF SAN-LUIGI-DEI-FRANCESI, ROME, ITALY

Simultaneous indoor and outdoor samples collected in the Church of San Luigi dei Francesi were analyzed for nitrous acid, sulphur dioxide, n itrogen oxides and ammonia in the gas phase and for ammonium, sulphate , and nitrate ions in the particulate matter. Indoor levels of nitroge n oxide, nitrous acid and ammonia were found to largely exceed those o utdoors. For NO, and SO, lower indoor levels were always measured, whi le for nitrate and sulphate, the indoor/outdoor ratios ranged from 0.5 to 3.5. These results show that indoor production of nitrous acid cou ld result from heterogeneous reactions indoors, on the walls and expos ed surfaces. Furthermore, they demonstrate that non-reactive species s uch as nitrogen oxide and particles penetrate indoors, where they rema in segregated and are very slowly depleted, due to their small deposit ion velocities.