Visitor impact on an underground prehistoric monument : the Hal Saflieni Hypogeum, Malta

Abstract

The microclimate inside the Hal Saflieni Hypogeum, Malta, was monitored both spatially and temporally over a three-year period. This included recording air temperature and humidity in the various chambers, wall temperatures and moisture content, speed and direction of air currents, carbon dioxide concentrations, and light levels. Records of the presence of water, as pools and droplets, were also kept. It was found that, either directly or indirectly, the presence of visitors, together with the associated opening and closing of doors and illumination of the site, causes the greatest disturbance to the otherwise stable underground climate. Other factors causing disturbance include changes in external atmospheric conditions and the presence of water. Readings of air temperature and relative humidity taken over the past year during which the site has been unvisited have confirmed these conclusions