Noise exposure can have an impact on cognitive development and function.
In experiments where animals were exposed to moderate to high noise levels for four to 30 days, their brains suffered changes to the occipital, prefrontal and hippocampus regions. In humans, exposure to aircraft noise has been shown to impair cognitive development. Road traffic is the common source of noise across Europe, and the second most detrimental environmental factor, after pollution.
The effect of noise pollution on children’s cognitive development is less known, especially considering this is a vulnerable life stage for brain maturation.
A new study, published in PLOS Medicine, has found that schools situated near noisy roads may be causing memory and attention issues for children.
A team of scientists measured the intensity and fluctuation of road noise in classrooms across 38 schools in Spain. The level of exposure was measured using markers both inside and outside of the schools, as well as nears the students’ homes, controlling for levels of traffic-related air pollution and sociodemographic.
Participating school children (aged seven to 10) were also asked to complete computerised cognitive tests four times across one year. The cognitive tests included working memory, complex working memory and inattentiveness.
The scientists found that exposure to higher-intensity levels of road-traffic noise both inside (above 30dB) and outside (above 55dB) of the school, but not at home, was associated with slower improvement of working memory, complex working memory and attentiveness. For example, a 5dB increase in outdoor noise levels resulted in an 11.4% slower development of working memory, 23.5% slower development of complex working memory, and 4.8% slower attention capacity development on average.
“This could be because noise exposure at school is more detrimental, as it affects vulnerable windows of concentration and learning processes,” says Dr Maria Foraster, from the Institute for Global Health Barcelona, Spain, and lead author of the study.
“On the other hand, although noise measurements were taken at the schools, noise levels at the children’s homes were estimated using a noise map that may be less accurate and, in any case, only reflected outdoor noise. This, too, may have influenced the results.”
Inside the classroom, these associations were more strongly linked to noise fluctuations rather than average noise levels.
“This finding suggests that noise peaks inside the classroom may be more disruptive to neurodevelopment than average decibel level,” says Foraster. “This is important because it supports the hypothesis that noise characteristics may be more influential than average noise levels, despite the fact that current policies are based solely on average decibels.”
The study underscores the need to re-examine local noise pollution inside and around school environments, especially in heavily populated urban environments, and how this might be mitigated.