Human exposure to harmful urban traffic noise pollution levels: a case study from seoul, South Korea

Among the various forms of environmental noise pollution in urban areas, road traffic noise (RTN) is the most dominant source, with it increasing the risk of various diseases such as stroke, heart disease, and diabetes. Considering these risks, this study aims to evaluate RTN levels across four monitoring sites classified by urban neighborhood categories, compare them with WHO-recommended thresholds, and analyze potential adverse health effects. We conducted a cross-sectional study by selecting residential areas, commercial areas, and industrial areas as the study sites, dividing them into areas with large populations and high traffic volumes according to land use types. We used WHO guidelines for no observed adverse effect level (NOAEL) for myocardial infarction (MI), for nighttime and the whole day (L_den), published in 2009 and 2018, and compared them to RTN measurement data from January to December 2022 collected at the four monitoring sites. Noise levels at the four study sites exceeded the three thresholds set by the WHO based on the exposure–response relationship between RTN and cardiovascular disease: the daytime and nighttime NOAEL values of 60 dB(A) and 50 dB(A), the nighttime threshold of 45 dB(A), and the overall L_den threshold of 53 dB(A). Furthermore, the degree of exceeding the standard value was higher in commercial and industrial areas than in residential areas. Given these detailed analyses, the high proportion of the population exposed to harmful RTN contamination warrants substantial investigation and policy-maker action on the potential risks, taking into account regional characteristics.