Every nursery school, primary school and day-care centre in Britain will have to conduct a "noise risk assessment" in case the din of children is damaging teachers' hearing, Europe's health and safety official said yesterday.

If noise levels are found to be above 80 decibels - a level recorded in many classrooms during one recent Danish study - head teachers will be obliged to take action to reduce noise "to a minimum", said Hans-Horst Konkolewsky, director of the European Agency for Safety and Health at Work.

If the noise levels rise above a new maximum of 87 dB, heads, or crèche owners, who fail to take action could face criminal prosecution.

Actions required could involve fitting acoustic tiles on classroom ceilings, giving staff longer breaks or reducing class sizes, said Mr Konkolewsky.

Traditional noise-prevention laws have focused on shipyards, steel mills and other obviously loud workplaces.

But the education sector is a hidden source of risk, said Mr Konkolewsky, especially where today's more raucous pupils are housed in hard-floored, echoing Victorian classrooms, built for the days when children sat silently, copying from a blackboard.

A European Union Noise Directive will come into force next February, replacing and substantially toughening up existing EU noise rules.

The directive, which was approved by the British and other EU governments in 2003, imposes a new obligation on all employers where noise is a potential hazard to conduct a scientific analysis of their workplace. The directive includes new, much lower levels of noise that trigger mandatory action.

Vladimir Spidla, the European Commissioner for employment, social affairs and equal opportunities, yesterday launched a Europe-wide "Stop That Noise" campaign.

The initiative is aimed, he said, "at people in industry, but in primary schools as well".

Mr Konkolewsky said: "A Danish study has shown that over half of schoolteachers and day-care workers have to raise their voices to communicate with colleagues, much more than in many industrial trades."

But he offered assurances that the EU would be "reasonable" in assessing what was possible in schools. Head teachers had to work with health and safety experts to find the right balance.

The new directive allows the entertainment sector an extra three years, until 2009, to find ways to reduce noise levels in venues that are hard to keep quiet, such as discos, bars and concert halls.