Danger of dust explosions on the London Underground

This article argues that the danger of dust explosions from combustible tunnel dust on the 
London underground has not been properly recognised and addressed. It suggests that the RMT 
union urgently investigates the dangers of dust explosions on the tube so that it is able 
to ensure the safety of its members and the pubic.


What is a dust explosion?
 

http://www.chemeng.ed.ac.uk/~emju49/SP2001/webpage/intro/intro.html

In the last 20 years industrial dust explosions have accounted for several hundred deaths 
and hundreds of millions of dollars of insurance money and yet they are one of the least 
recognised of industrial fire hazards. They can occur within any process where a combustible
dust is produced, and can be triggered by any energy source, including static sparks, 
friction and incandecent material.

There are a few basic rules to observe to see whether a dust is capable of causing a dust 
explosion:

London Underground does not recognise tunnel dust as a potential fire and explosive hazard. 

http://www.london.gov.uk/assembly/past_ctees/btrtubemtgs/2001/btrtubedec18/minutes/btrtubedec18mins.pdf

Minutes: The Tube Future Priorities
Investigative Committee
18 December 2001

Mike Strzelecki, LUL: It's dust, it's caked on dust, it's a mixture of iron from the 
action of the rail on the wheel and vice versa, it's human dust in terms of skin and 
hair particles which we all shed routinely, and it's quartz from the brake locks on 
trains. Now, a lot of research has been done into this over the years, including very 
recently, indeed we had an Institute examine all the research that's been done to 
determine whether this stuff is dangerous to people's health or not, and the answer 
is that there is no evidence that it is, and the most sort of compelling evidence that 
it isn't, is that the staff who work on the underground who are obviously are in the 
underground environment much longer than customers, there is no evidence of any 
medical problems occurring from long hours and many years of exposure, working in the 
underground.

Eric Ollerenshaw: Is there a fire risk?

Mike Strzelecki, LUL: No, it doesn't burn.

Having reviewed available evidence - concentrating particularly on incidents in 2003 - this 
article calls for an urgent investigation into the fire and explosive dangers of tunnel dust 
on the London Underground. 

Is tube tunnel dust dangerous?


London Underground have conducted inquiries into the possible dangers of breathing tunnel 
dust. These inquiries provide an insight into the composition of tunnel dust. Care should 
be taken in evaluating the findings since the studies concentrate on suspended dust in 
stations and drivers' cabs. It is likely that the dust actually inside the tunnels is 
different since it is a different environment. There is little movement of air, tube trains 
travel along sections between platforms and dust probably accumulates in the deeper parts 
of tunnels. Tunnel dust may have a higher iron content from wear of the rails and wheels 
and less organic content from passangers clothes, etc. 

Studies into London tube tunnel-dust reveal that it is composed of iron, silica and organic 
products. Different studies have arrived at different ratios of these constitiuents with 
London Underground finding a roughly 50% iron content and a study conducted by IOM finding 
a 90% iron content. 

It is generally accepted that dust must be smaller than 0.1mm in diamater to pose an explosive 
hazard, with smaller particles being more explosive. The dust inhalation studies on the London 
tube have been concerned with much smaller particles than this. 
[PM10s are particles with a diamater less than 10 micrometres, PM2.5 have a diamater less that 
2.5 micrometre. 1 micrometre = 1 millionth of a metre, 1x10-9m] 

http://www.iom-world.org/pubs/IOM_TM0302.pdf 
Institute of Occupationa Medicine report 'Study of tunnel dust in the London Underground'

Composition of tunnel dust: Samples from station platforms showed that almost all (typically, 
about 90%) of the dust in the PM 2.5 samples was analysed as iron. There were trace amounts 
of chromium (0.1 ? 0.2%), manganese (0.6 ? 1%) and copper (0.1 ? 1.5%).  No zinc was detected 
on any of the samples (<0.1%). Quartz, analysed in respirable dust, accounted for only 1-2%; 
these measurements were approximate, being close to the analytical detection limit.  
...
The distributions from the three stations are remarkably similar, with the data from Hampstead 
being slightly finer. The median diameter for the dust from Oxford Circus and Holland Park is 
0.4µm and for Hampstead 0.35µm. In each case about 80% of the particles have a diameter less 
than 1µm. Again, note that this underestimates the aerodynamic diameter of the denser particles.

[µm is micrometre - one millionth of a metre (1×10-6 m), equivalent to one thousandth of a 
millimetre.]

Does it burn? is the big question. If it burns, then it is explosive when suspended or thrown 
into the air. 

http://www.chemeng.ed.ac.uk/~emju49/SP2001/webpage/deh/deh2.html

Materials that can cause dust explosions:

Iron burns, organic materials burn.

http://www.tfl.gov.uk/tube/company/reports/dust-report-2001.asp
Tunnel dust silica crystals have a coating of iron on their surface, which makes them less 
likely to cause fibrotic lung disease. 

Since the silica is coated with iron, it will burn.


Have there been dust explosions on the tube?
 

Eyewitness accounts certainly suggest that there have been many dust explosions on the tube. 
Witnesses often speak of smoke, dust and fires. There have been many trackside fires. If not 
dust, then what's burning? It's almost as if there's a conspiracy to deny this real danger 
to tube users. 


25 January 2003 Chancery Lane
http://www.guardian.co.uk/transport/Story/0,,882674,00.html

Passengers involved in a horrific rail crash on London Underground told last night how they 
escaped death thanks to a miraculous chain of events after a Tube train lost a wheel and hit 
the tunnel wall.

Yesterday's crash, which left 30 people injured and prompted fresh questions about 
under-investment in rail safety, happened shortly after 2pm as the train was travelling 
from St Paul's to Chancery Lane.

Witnesses said sparks flew from beneath the train, which was carrying 800 people, before the 
three rear carriages left the tracks, bouncing from wall to wall and sending passengers flying 
from their seats. Last night one man was being treated for a suspected broken leg after being 
smashed into the opposite side of the train. 

Amid scenes of panic as the carriages were plunged into darkness and smoke billowed through 
smashed windows and doors, some passengers helped others out along the track. 'I was absolutely 
panicking,' said Claire Ellis. 'I was thinking: this is it, this is the day it happens.'

...

The hospital said many passengers had suffered smoke inhalation. 

...

Economics student Humaiun Kobir, 25, was on the last carriage. 'The train was being thrown from 
side to side, hitting both walls of the tunnel. All the lights went out and thick black smoke 
was pouring in. I could hear the driver over the radio shouting "Mayday, mayday" then the train 
stopped.

'He asked all the passengers to get to the front as quickly as possible. My first thought was 
that it was some kind of terrorist attack. We were all terrified that another train was going 
to smash into the back of us. But we knew there was a fire and no one wanted to run into that.' 

http://news.bbc.co.uk/2/hi/uk_news/england/2696323.stm

The driver was treated for smoke inhalation and was breathalysed, but the results were negative.


http://news.bbc.co.uk/2/hi/uk_news/england/2694503.stm
Tube crash: Eyewitness accounts


 "When the train arrived at the station I think it came off the track and hit the tunnel.

 There was some kind of fire.

 Most people's faces went black and they couldn't breathe properly.

 There was smoke inside the carriage. We were lucky to survive.

 Most of the people in my carriage were crying and praying for survival.

 In my carriage there were a lot of kids and they were crying.

 The train stopped suddenly and bumped six times before it stopped so people were really 
scared and didn't know what was happening.

 The driver himself couldn't even breathe himself. His face was all black." 
 
...

 "There was an immense vibration and banging as the train shuddered to a halt.

 The driver said, 'Mayday! Mayday!', then, 'Help! Help!' there was a fire at the back of 
the train, and told everyone to leave as fast as possible.

 There were many people panicking in my carriage, which was very full.

 The carriage began to fill up with smoke, as did the platform.

 And we could see those on the platform running and screaming as we tried desperately to 
open the doors of the carriage.

 I truly thought the sight of the platform filling with smoke might be the last thing I saw."


19 June 2003
http://news.bbc.co.uk/2/hi/uk_news/england/london/3007970.stm
More than 90 passengers had to be evacuated from a Tube train and walked to safety through 
the tunnel following a track fire, London Underground (LU) said.

Fire crews were called to a small track-side fire on the Bakerloo Line at Embankment at about 
1340 BST, a LU spokeswoman said.

During the incident, one of the trains stalled in the tunnel and 94 passengers were stranded 
on board for 40 minutes before being walked down to Waterloo station.

The incident was one of three to affect rail and tube networks in London during the day.



http://news.bbc.co.uk/2/hi/uk_news/england/london/3207079.stm

The Rail Maritime and Transport (RMT) union also claimed a "potentially serious" incident 
was averted on 11 October when a driver decided to evacuate a train and take it out of 
service because of a defect.

It said the train had a seized axle which could have resulted in a derailment if it had 
continued, but LU accused the RMT of exaggerating the incident. 



http://news.bbc.co.uk/2/hi/uk_news/england/london/3204794.stm

Eyewitness Harry Anscombe, 22, arrived at the station at 1015 BST as emergency services 
pulled up outside.

"There were lots of blackened faces and there was one man with bandages on his face and blood 
streaming down," he said. 

http://news.bbc.co.uk/2/hi/uk_news/england/london/3205280.stm
Mr Anscombe asked one of the passengers what had happened, but the man said he did not know 
because it was "so black down there".

The passenger said the derailment had caused a huge amount of dust to fly up, making it 
difficult to see. 


Why we need an inquiry
 

This article raises the issue of the unacknowledged danger of dust explosions on the 
London tube. There is no indication that London Underground has investigated the danger 
of dust explosions. On the contrary, evidence is presented that suggests that London 
Underground has been complacent and negligent in its approach to public safety. The 
article suggests - through witness accounts - that dust explosions have played a role 
in tube incidents. 

Should it be accepted that dust poses an explosive hazard on the London tube, then safety 
procedures must change. Maintence needs to be performed flawlessly so that nothing disturbs 
the dust and that there are no sources of heat to ignite it. Drivers and other staff need 
to be trained properly so that they can better ensure their own and the public's safety. 
Drivers need to know that they should not drive through visible clouds of dust.

http://news.bbc.co.uk/2/hi/uk_news/england/2752357.stm

Ten minutes later, a driver on a following train reported Bethnal Green and Liverpool 
Street stations were "really dusty and murky".

The controller reports "there might be a problem with the train in front" and the driver 
replied "it ain't half kicking up a lot of dust". 


It is suggested that the RMT urgently investigates the dangers of dust explosions on 
the London tube.