London's loudest Tube lines revealed: Commuters warned to wear earplugs as one route is noisier than a chainsaw

Screeching rails and booming updates from the driver... regular Tube riders can be forgiven for trying to drown out the racket with their headphones.

Many commuters will be able to recall catching the eye of a fellow passenger with their fingers in their ears. 

But just how loud is it down there on the London Underground? MailOnline decided to find out.  

Eqiupped with a decibel reader, we rode the length of five Tube lines spanning from Zone one to Zone four to compare how loud they were, and how much regular commuters were putting their hearing at risk. 

After measuring the decibels (dB) on the Circle, District, Central, Victoria and Northern lines, it was clear some lines were louder than a chainsaw or jack hammer - industrial equipment that users are advised to wear ear protection when using. 

Simon Rehill, General Manager and sound expert from Pulsar Instruments, said passengers should be wary when travelling on loud trains for long periods and opt to wear ear protection. 

'One reason why the Tube is so loud and noisy is because the sound can't go anywhere. It's trapped and has to travel to the other end of the tunnel to escape,' he told MailOnline.

'The noise will bounce around the walls and build up causing friction and heat.' 

Passengers are at risk of damaging their hearing if exposed to loud sounds higher than 85 dB for 24 hours. 

A 'safe' level of noise for our ears sits between 50-60 decibels, which is the same volume as a normal conversation.

But the noise levels measured on all five lines exceeded this with the average varying between 69.7 dB on the District line and 88.1 dB on the Northern line.  

The Victoria line was by far the worst one tested overall. Most passengers were silent and struggled having a conversation with the person next to them between Oxford Circus to Tottenham Hale and back. 

This line had a brief spike in sound levels that reached 117.6 dB - which is louder than a chainsaw - and an overall average of 87.4 dB. 

At one point the Circle line from High Street Kensington to Monument was as loud as a jack hammer and reached a peak decibel reading of 124.8. The average was 73.5 dB, which is the same loudness as a vacuum cleaner. 

The District line was the most comfortable to travel on from Monument to South Kensington with an average decibel reading of 69.7 - the lowest of the lines tested. 

The Northern line on the other hand was louder than a chainsaw with a peak of 116.9 dB and an average of 88.1 dB between King's Cross St Pancras in Zone one and Finchley Central in Zone four.

Simon added: 'If you're working in a noisy environment and are exposed to the Tube in the same day for a long time, you need to be really careful because you don't want to damage your hearing.' 

Since material and clothing absorbs sound, the Tube can seem quieter when more people are travelling on it. 

It's considered unsafe for workplaces to be louder than 85 dB for more than eight hours. 

If a workplace exceeds this limit employees need to be provided hearing protection to wear over throughout their shift. 

If the noise increases, the amount of time someone can be exposed to the sound decreases. 

For instance if a noise level is constantly at 91 dB a worker can only be exposed to this for two hours with hearing protection.

In May the London Assembly Environment Committee expressed concern about Tube noise levels and carried out an investigation. 

It asked for Transport for London (TfL) to make noise data publicly accessible. 

Zack Polanski AM, Chair of the London Assembly Environment Committee throughout the investigation, said: 'The London Underground provides incredible transport links across the city and plays a vital role in London's economy.

'However we cannot ignore the issue of noise pollution and the impact this has on the health and wellbeing of Londoners. 

'The World Health Organisation clearly outlines the effects prolonged exposure to significant noise can have on people's wellbeing.

'We hope to work collaboratively with TfL to make the necessary changes that will help keep Londoners safe and well.'