In order to apply noise hotspot prioritisation factors objectively and systematically, a new index is introduced. The Comparative Noise Exposure Unit (UCEden) is an index based on the Lden noise index and is evaluated on the basis of strategic noise mapping. The exposure of a site is characterized according to the number of people disturbed and the Lden level to which these people are exposed. For this purpose, the UCE is defined according to the formula indicated in the legend where the UCEden is without unit, and N corresponds to the number of dwellings on the site, Pi corresponds to the number of persons domiciled at dwelling i, and Li is equal to the noise level Lden at the most exposed façade of dwelling i. Although the Li level is expressed in decibel (dB), the UCEden is actually an indicator without dimension, combining the exposed people and the exposure level of the dwelling they occupy. For more information, please access the elaborated noise action plans at www.emwelt.lu.