The World Health Organisation classifies Low-frequency noise (LFN) as an environmental problem that
causes various health impacts. Industrial sites and activities are among the various identified sources
of LFN. However, industrial noise has been more studied on higher frequencies than lower frequencies.
To fill this gap, this paper evaluates the impacts of LFN emitted by industrial sources in neighbouring residential areas. The method was supported by a quantitative evaluation by using three indicators: L10–
L90, dB(C)–dB(A) and the tonal characteristics of the sound. This quantitative evaluation was complemented
by a qualitative assessment supported by a questionnaire addressed to the residents living near
the industrial sources. The study was carried out in two industrial parks in Guimarães, Portugal. The
quantitative evaluation showed that industrial activities were a source of LFN, but the low-frequency
content of the noise was not very significant. The noise had fluctuating characteristics and was found
to be tonal in one location. In turn, the complementary qualitative evaluation revealed that residents felt
disturbed and linked effects such as stress, irritability, and sleepiness to noise. The study provides new
insights into the impact that LFN may produce in residential areas located near industrial plants and
highlights the need of adopting effective planning policies to prevent residential areas from industrial
noise.