Switzerland's topography means that the central plateau is densely populated. Industry, farming, transport and leisure activities compete for space with residential areas. All of these can be sources of pollution. The mountain environment is especially fragile. Climate change brings the threat of landslides and flooding, as well as threatening the important tourism industry. Air pollution is a constant source of concern. The different types of pollution are dangerous to human health and damaging to the environment as well as to buildings and monuments.