Road-traffic noise significantly slows the development of crucial memory and attention skills in primary school children, research has found.
The study of almost 2,700 children aged between seven and 10 in 38 schools in Barcelona, Spain, is the first to assess the impact of traffic noise on child cognitive development over time and to determine the impact of peaks in noise.
The children in the study are in a critical stage for the development of memory and attention skills, which are essential to learning. The research found that children exposed to about three times more traffic in the street than other pupils had memory development that was 23% slower and attention ability development 5% slower over a year.
Noise is the second most damaging environmental factor to health, after air pollution, and, for example, was already known to increase heart attacks and diabetes in adults. The UN said in February that urban noise pollution was growing into a “global public health menace”, leading to 12,000 early deaths a year in the EU alone, and affecting many cities from Bangkok to New York.
But research on the impact of road noise on children was limited until now. The scientists said many schools suffered noise pollution and that measures such as rerouting traffic away from schools could help reduce noise and air pollution.
“We do not appreciate that noise can actually be toxic from a physical point of view,” said Dr Maria Foraster, from the Barcelona Institute for Global Health, who led the study. “We think that we adapt to it, but research has shown that we don’t completely – we still have a physiological response.”
The research revealed that peaks of noise heard inside the classroom, such as the passing of loud trucks or vehicles accelerating away from traffic lights, had more impact than a higher average level of noise. This may be because the peaks divert attention more, said Foraster, and is important because current policies are based solely on average decibels.
The scientists also found higher noise levels at school were more damaging than at home. “This could be because it affects vulnerable windows of concentration and learning processes,” she said.
Prof Iroise Dumontheil, at Birkbeck, University of London, UK, said: “This carefully designed study provides convincing evidence. Considering that many European children living in large cities are exposed to high road-traffic noise levels, this study has implications for public policy to reduce road-traffic noise near schools.”
The study, published in the journal PLOS Medicine, tested the children four times across a year and measured noise levels outside the school and in classrooms. The tests assessed attention – the ability to focus on a specific task – and working memory, which is the ability to hold information in the mind and use it.
“These two functions are important for learning and develop very rapidly during the primary school years,” said Foraster. They underpin problem solving, reasoning, mathematics and language comprehension.
The scientists concluded: “Policies to reduce road-traffic noise at schools – outside and inside classrooms – could substantially benefit cognitive development and future health.”
Noise affects large numbers of people, with at least 20% of the EU population suffering traffic noise levels that are harmful to health. The proportion is much higher in cities.
The scientists did not have data on the noise exposure of the children before the study started, but nearly all of them had attended the same school for at least a year. The study took into account the effects of air pollution, unlike most previous studies, and levels of family income and education.
The research follows previous work that showed higher levels of aircraft noise at school affected reading comprehension and cognitive development. Rat experiments have also shown that exposure to moderate-to-high noise levels leads to changes in the brain. But the scientists said they would like to see their findings replicated in different cities and towns, where schools may be built differently and windows opened more or less often.
The rise of electric cars will reduce noise travelling at lower speeds, when the engine noise of petrol and diesel cars dominates, Foraster said. But at speeds above 40-50km/h, the noise generated by tyres on the roads is high for all types of car.
“The fact traffic noise harms health and wellbeing is not talked about often enough,” said Prof Trevor Cox, at the University of Salford in England. “Arguably, the effect on student learning in schools is the worst harm. This is because any lack of attainment is detrimental to health and wellbeing for the rest of the students’ lives. Addressing noise is particularly important for equality, because schools in disadvantaged areas are usually on noisier sites.”