Method for marking sites

A method for determining changes of a site, which is characterized in that a) the site is treated with a composition and b) the site thus treated and/or the untreated areas adjacent thereto are exposed to UV light and the deviation b1) of the light intensity of the emitted light of a partial area of the site from the mean light intensity of the emitted light of the site area and/or b2) the light intensity of the emitted light of a part of the adjacent, untreated area from the mean light intensity of the emitted light of the adjacent untreated areas and/or b3) the light intensity of the emitted light of the site immediately after the treatment with the composition from the light intensity of the emitted light at a later time and/or b4) the light intensity of the emitted light of the adjacent untreated area immediately after the treatment of the site with the composition from the light intensity of the emitted light of the adjacent, untreated area at a later time are determined, the composition being an aqueous dispersion comprising: a1) at least one binder, a2) at least one substance emitting visible light on UV exposure and a3) optionally a dispersant.