Based on the systematic review of evidence available at the time of the development of the environmental noise guidelines (2), the following recommended levels for specific noise sources can be defined.

For average noise exposure, the following sound pressure levels are recommended (2, 6):

< 53 dB Lden for road traffic noise

< 54 dB L_{den} for railway noise

< 45 dB Lden for aircraft noise

< 45 dB L_{den} for wind turbine noise

For night noise exposure, the following sound pressure levels are recommended (2):

< 45 dB Lnight for road traffic noise

< 44 dB L_{night} for railway noise

< 40 dB L_{night} for aircraft noise.