The world tourism industry is expanding at rate of 4% every year. Cultural sites remain a favourite destination. Some wall painting sites are positioned at the top of the tourist agenda and the effects of visitors are manifest. Other sites, although less massively visited, are still victims of alterations as a result of growing tourism.
In observing the effects of visitors and their potential amelioration measures, some variables need to be defined. Four main types of sites are found: exterior or interior sites, and contained or separable sites. Further, sites which only attract tourists may also be distinguished from sites which have other uses. Each site category will have a specific microenvironment, physical characteristics, administration type, visitor management etc. Therefore, small or large, newly opened or old, sites may receive similar attention from the public but they do not have the same vulnerabilities.
Three main types of effects are described: direct effects, either intentional or unintentional; indirect effects due to changes in the microenvironment÷these may be caused by metabolic activities or by comfort requirements; and indirect effects due to changes in the paintings and site÷these may result from alterations in the presentation of wall paintings or deleterious gradual effects of tourism. Each specific site has definite effects and corresponding amelioration measures.
Effects of tourism have been recognised and tackled progressively. Amelioration techniques range from mitigation against immediate effects (barriers or supervision), attempts to lessen both direct and indirect effects÷such as grouping, staggering or rotating visitors÷to visitor management strategies aiming at ameliorating alterations in the microenvironment, and long-term preventative interventions.
Certain mitigations may appear conflicting; for example, sites may either forbid guided tours or, on the contrary, encourage them; they may close off certain areas or conversely open more spaces and excavate new sites to redirect the flow; certain sites may limit the number and time of stay of their visitors, whereas others prefer to limit opening hours but not the numbers, and so on.
Monitoring both visitor dynamics and microenvironment is crucial in order to define appropriate and effective amelioration measures. However, this is rarely implemented except for subterranean sites. It seems that effects of tourism are observed but not examined; thus some preventative measures appear useless or even harmful.
Five cases were studied in situ in an attempt to assess both possible effects of visitors and amelioration measures. The sites selected correspond to the various types: open archaeological site (Pompeii); separable interior sites (the Sistine Chapel, Avignon Papal Palace and Westminster Abbey Chapter House), and a subterranean site (the Tomb of Nefertari). Three of these sites - Pompeii, the Sistine Chapel and Avignon - also have significant other functions, for religious celebrations, recreational activities, or as private venues. Yet tourism remains their main function. The others are tourists-only sites. These case studies confirmed previous conclusions on visitor effects and mitigation measures. They indicate how specific sites have dealt with the problems.
In conclusion, it is argued that more investigations of environments are needed is relation to visitors, in fields others than subterranean environments. The results of these examinations should help implement specific amelioration measures. It is important for conservators to be involved in the process of environmental monitoring and visitor management decisions.