Children in schools under airport flightpaths have more difficulty learning to read and score less well in memory tests, researchers reported today in the Lancet medical journal.

The effect of loud aircraft noise impaired their reading comprehension. As a result, schools near big international airports were "not healthy educational environments", said a team from Queen Mary's School of Medicine, London.

They assessed the effects of aircraft and road traffic noise on more than 2,800 children aged nine and 10 at 89 schools near Heathrow in London, Schiphol in Amsterdam and Barajas in Madrid.

Those closest to the flightpaths experienced the most noise. Children at primary schools near Heathrow lost two months in reading age for every extra five decibels in the noise level, while the children near Schiphol had their reading age delayed by one month. Corresponding Spanish data was not available.

Aircraft noise was also associated with a significant impairment in the ability to identify previously learned information.

Heavy road traffic noise did not have an effect on reading, but the researchers were surprised to find that children in schools near noisy roads in all three countries did better in memory tests.

The study suggested: "Aircraft noise, because of its intensity, the location of the source and its variability and unpredictability, is likely to have a greater effect on children's reading than road traffic noise, which might be of a more constant intensity."

Children might learn to block out the unwanted stimulus of aircraft noise and extend this tuning-out strategy to other stimuli, including their teachers. The report found both aircraft and traffic noise was linked to increased stress and reduced quality of life in the children.

It concluded: "Schools exposed to high levels of aircraft noise are not healthy educational environments."

Stephen Stansfeld, a professor at Queen Mary's who led the study, said: "These exposure-led associations, in combination with results from earlier studies, suggest a causal effect of exposure to aircraft noise on children's reading comprehension.

A co-researcher, Charlotte Clark, said: "Noise exposure across childhood is an important public health issue. Finding similar effects of aircraft noise on reading across three European countries strengthens our conclusions that this is a specific causal effect of aircraft noise on children's school performance."