The assessment of noise from industrial plants by direct measurement and by calculation

The noise levels measured at a distance of 1000m from an industrial plant can vary within a range of 20 dB(A) due to the effects of weather and extraneous sources. This paper examines the use of various statistical parameters for assessing the noise due to the plant and describes a method of minimising the effect of extraneous noise due to traffic. The choice of parameter influences the attenuation data to be used in calculating the noise from new plants. Some typical measurements from a large industrial plant are presented. The paper emphasises the need to agree on a single parameter which can be used for calculations, for assessing measured noise levels, and for comparison with legal or noise criteria, and recommends the general adoption of L_eq.