In accordance with European legislation, the Environment Agency has updated the strategic noise maps for the fourth cycle of Directive 2002/49/EC of the European Parliament and of the Council of 25 June 2002 relating to the assessment and management of environmental noise. These maps refer to the year 2021 and indicate, using a standardised colour scale based on the Lden indicator, the exposure to ambient noise in decibels of major roads with more than 3 million vehicles per year located within agglomerations.

The indicators used to describe the annoyance caused by exposure to noise are :

Lden in decibels (dB), a representative average noise indicator for a 24-hour day, evaluated over a full year and for which the evening period is penalised by 5 dB(A) and the night period is penalised by 10 dB(A); and the

Lnight in decibels (dB), a representative average noise indicator for an 8-hour night, assessed over a full year and associated with sleep disturbance.

The indicators are based on three periods of the day: a day" period of 12 hours (7am to 7pm), an "evening" period of 4 hours (7pm to 11pm) and a "night" period of 8 hours (11pm to 7am)."

https://environnement.public.lu/fr/loft/bruit/valeurs-limites-bruit.html