The Protection of Artworks and Cultural Heritage is a first priority issue in Italy due to the exceptional wealth and substantial unicity of its artistic heritage.
It is known that an approach based on a single point measurement without investigating local and temporal variations can give only partial information. A more comprehensive assessment should include a generalisation that covers the territory or, in a museum the study of more than one room. This can be made on the basis of the knowledge of the spatial distribution of concentrations in a specific area where an artwork is located. In contrast to active samplers in which air is brought into contact with a detector or collector device by means of a pump, diffusive samplers rely on diffusion to bring the pollutant into contact with the collector. Compared with the pump-dependent active sampling procedure (i.e. diffusion denuders), main advantages of the method are cost effectiveness, simplicity and the potential for large-scale measurements carried out at the same time. Passive samplers are an ideal tool for determining the pollutant distribution over a large area and to assess integrated concentration levels over long period of time. The main advantage of these sampling devices is that they are inexpensive and easy to use. In addition, the passive device is not constrained to sites where electrical power is available.
A simple, inexpensive passive sampler for many pollutants has been developed. The sampler is a modification of the open-tube design obtained by using a filter treated with appropriate reagents to trap the pollutant. The device developed in this study is similar to that described by Bertoni et al  in previous laboratory and field studies of atmospheric benzene, toluene and xylenes (ANALYST®). The body of the sampler is a cylindrical glass vial with a threaded cap at one end. The pollutant is collected on a disc of impregnated microfibre or carbon paper filter placed at the bottom of the vial and held in position by a stainless steel ring. To avoid turbulent diffusion inside the vessel, the open end was protected using a fine stainless steel screen. Before and after sampling the screen is replaced with a polyethylene cap.
The typical questions an assessment by using passive sampling can answer are:
Examples taken from monitoring campaigns in the framework of the European Project MIMIC for NO2, NOx, SO2, HONO and O3 at the Uffizi Gallery, at the Alcazar of Segovia, at the National Museum of Denmark, at the Sandham Chapel (UK) and for NO2 and SO2 in Siracusa, (Italy) will be presented and discussed.
 Bertoni G, Tappa R, Allegrini I, (2000) Annali di Chimica 90:249-263
Author to whom correspondence may be addressed:
Franco De Santis
via Salaria Km 29,300
00016 Monterotondo Scalo, Roma
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© February 12th, 2002