I know it has been posted in the past about the loudness of orchestras, but this is pretty insightful with regards to the Proms.
Would be quite amusing story if it was not so serious with future consequences for other performances affected by costs/time/etc due to the new EU health regulation.

From the Daily Telegraph posted 28th August 2008.

Under the directive which came into effect in April, the broadcaster must ensure performers are not exposed to excessive levels of noise.

Noise control officers have been sitting in on rehearsals to take volume measurements and ensure orchestras keep below 140 decibels – the noise of a gunshot of firecracker.

A spokesman said: "If they go over this danger level we have to ask them to play more quietly."

The BBC has also been forced to erect screens between the musicians and hand out earplugs to make sure performers are not exposed to excessive noise.

The corporation has also had to transport musicians to larger rehearsal spaces so that the two-month long programme at the Royal Albert Hall in London meets European standards.

Describing the changes, Terry Wogan told listeners on his BBC Radio 2 breakfast show: 'Last weekend I was privileged to be at the wonderful BBC Proms along with Roger Wright who is the controller of BBC3.

"He was telling me about the EU directives on loudness. They are going to have to tone down the loudness at the Proms because it might be affecting people's ears."

He added: 'Roger Wright told me, "I should warn you that matters are about to take a turn for the worse at the Royal Albert Hall."'

However the BBC said the changes, while time consuming and expensive, will not alter the audience's experience.

Cheers
DT