As cities become rapidly more densified, there is now construction very close to roads and thoroughfares. Although scientists have already known that traffic noise can have a negative impact on human health, a team of researchers led by the Chalmers University of Technology in Sweden has now found that exposure to even as little as 40 decibels of such noise – the usual level of background noise in an office environment or kitchen – can have a detrimental effect on cognitive performance.
The experts conducted a laboratory experiment in which participants took concentration tests while being exposed to background traffic noise, consisting of two audio sequences simulating trucks passing at a distance of ten and fifty meters. More specifically, they had to look at a computer screen and react to certain letters, and assess their perceived workload afterward.
The results showed that the participants had significantly poorer results on the test, and felt that the task was more difficult to carry out, with traffic noise in the background.
“What is unique about our study is that we were able to demonstrate a decline in performance at noise levels as low as 40 dB, which corresponds to the regular noise level in an office environment or a kitchen,” said lead author Leon Müller, a doctoral student in Applied Acoustic at Chalmers.
“The audio sequence simulating the closer passages, where the sound changes significantly as the vehicle passes by, was usually the one that bothered the test subjects the most. This could be because traffic that is further away is perceived as a more constant drone.”
These findings highlight the negative impact of traffic noise on health and job performance. In recent years, the distance between roads and newly built housing has been allowed to shrink in many cities in Sweden and beyond. For instance, the current Swedish regulations for where construction is permitted are based on the average noise level over a 24-hour period and fail to take into account individual passer-bys or the peaks of low frequency noise indoors.
Since such noise is mainly generated by heavy traffic at low speeds, it is very difficult to avoid even with well-insulated windows and buildings that comply with the construction norms and guidelines for sound isolation.
“The calculations for different types of facades show that it is difficult to achieve ideal indoor sound environments near heavily trafficked roads,” said Jens Forssén, a professor of Applied Acoustics at Chalmers and lead author of a study modelling such low-frequency noise. “Reducing speeds is not a solution, as our calculations show that the indoor noise exposure can even increase at lower speeds.”
According to the researchers, noise and the sound environment are factors that are often considered too late in the planning process. While construction adjustments to better utilize the space in terms of noise pollution could certainly help, the most effective solution would be to avoid urban densification in areas where traffic noise would have too great an impact on health and wellbeing.
The study is published in the International Journal of Environmental Research and Public Health.
Traffic noise has several potential health impacts. Here are some of the most significant:
The World Health Organization recognizes traffic noise as a major cause of sleep disturbances. Lack of quality sleep can lead to various health issues such as fatigue, cognitive impairment, depression, and increased risk of chronic conditions like cardiovascular disease.
Chronic exposure to traffic noise can potentially lead to cardiovascular diseases. It is believed that noise acts as a stressor, causing the body to release stress hormones which in turn affect heart rate and blood pressure. Over time, this can increase the risk of hypertension, heart attacks, and strokes.
Long-term exposure to high levels of traffic noise can potentially lead to noise-induced hearing loss. This can occur when the delicate structures within the ear are damaged by prolonged loud noise.
There is evidence to suggest that chronic noise pollution, including traffic noise, can lead to an increase in stress levels, anxiety, and depression. Moreover, it can affect concentration, leading to decreased performance and productivity.
Some studies have suggested that chronic exposure to traffic noise may affect cognitive development and learning in children. Noise can be distracting and disruptive, potentially affecting concentration, attention span, and academic performance.
Apart from specific physical and mental health issues, noise pollution from traffic can also significantly affect people’s quality of life. Chronic noise can cause annoyance, disrupt daily activities, and overall decrease well-being.
While further research is needed to fully understand the extent of these impacts and their mechanisms, it is clear that traffic noise has potential negative implications for public health. Mitigation strategies can include things like improved urban planning, the use of noise barriers, noise-reducing asphalt, and promoting quieter modes of transport.