Characterization of Indoor Air Quality in the Church of San luigi Dei Francesi, Rome, Italy

Abstract

Abstract Simultaneous indoor and outdoor samples collected in the Church of San Luigi dei Francesi were analyzed for nitrous acid, sulphur dioxide, nitrogen oxides and ammonia in the gas phase and for ammonium, sulphate, and nitrate ions in the particulate matter. Indoor levels of nitrogen oxide, nitrous acid and ammonia were found to largely exceed those outdoors. For NO1, and SO2 lower indoor levels were always measured, while for nitrate and sulphate, the indoor/outdoor ratios ranged from 0.5 to 3.5. These results show that indoor production of nitrous acid could result from heterogeneous reactions indoors, on the walls and exposed surfaces. Furthermore, they demonstrate that non-reactive species such as nitrogen oxide and particles penetrate indoors, where they remain segregated and are very slowly depleted, due to their small deposition velocities.