Goodbye to British Standard 6164:2011 and welcome to the BS 6164:2019.
A new revision has been released including the advances in technology and equipment available to the tunnelling industry.
Eric Ball, occupational hygienist and partner in Park Health and Safety Partnership, explains how the new update to the BS 6164:2019 brings additional help and considerations to health exposures occurring in the tunnelling industry.
“I think it is a very good mixture of providing important information, guidance, and signposting to further information,” says Ball. “It will help achieve legal compliance on standard issues such as noise and vibrations.
“But it also works as a driver to the industry to further improve health management in tunnelling.”
However, some changes of the BS 6164:2019 present a difficult target for the industry to achieve. “It would be interesting to see how the industry will respond to those changes in terms of improving the technological solutions required to satisfy the requirements of BS 6164,” says Ball. “Of course nothing changes overnight. The industry will take a while to understand the implications of what is new into the BS 6164 and how it will change the way we work and the methodology that we use or the standards that we have in place.
“Technological solutions will also take a time to be developed to help compliance with some of the requirements of BS 6164: 2019.”
Ball adds, “If we compare the BS 6164: 2019 with the previous version BS 6164:2011, we can see that in eight years there has been a greater appreciation of the risks from silica not just for typical construction operations but also for the implication of dust exposure on SCL works.”
“The appreciation of dust risks in BS 6164:2019 is one of its greatest successes. It now makes reference to lower exposure limits for dust suggested by the British Occupational Hygiene Society (BOHS).”
The industry traditionally aimed to control dust to 10mg/cbm for inhalable dust and to 4mg/cbm for respirable dust. However, occupational hygienists have always considered that it is too high, and BS6164 echoes this by directing the industry to aim for 5mg/cbm and 1mg/cbm for inhalable and respirable dusts. Ball adds that it is also important to see how the industry will manage the diesel exhaust emissions. The industry will need a very strong partnership with the plant suppliers to achieve the new exposure limits, particularly with regards to elemental carbon. “For me it is positive to see that BS 6164:2019 has an established guidance level for elemental carbon,” says Ball. “We have not yet had one in our lists of exposure limits so we have had to often rely on limits used in other industries or countries.
“It’s good to realise that the tunnelling industry now has a reasonable limit of carbon emissions as the BS 6164 limit for elemental carbon (0.1mg/cbm) is tighter than the limit used in mines (0.15) but it’s not as good as the US limit of 0.02. Thus, the limit is not that low to be impossible to achieve but is not so high that it can be achieved by accident.”
Ball adds that it’s a good limit to challenge the industry. It is a short-term exposure limits rather than the usual eight-hour averages we have previously. This means that the industry really has to drive on technical and engineering controls to prevent exposure, not just simply rely on ventilation. It also presents a challenge for monitoring as well.
Ball admits that it might be difficult for the industry to get the limits for nitrogen oxides from diesel exhaust emissions. The new limit for Nitrogen monoxide is currently 25ppm (eight hours TWA) but getting reduced to 2ppm in 2023. The nitrogen dioxide currently doesn’t have a limit applicable to tunnelling but in 2023 this will be 0.5ppm (8hr TWA) and 1ppm (15min STEL).
“These are difficult limits for the tunnelling industry, but I don’t have any doubts that the industry will achieve it. Unlike elemental carbon, which is a standard to reach in tunnelling, the limits for NOx are legislative,” says Ball. “The difficulty of achieving this can be seen in the fact that the tunnelling industry has been given an additional four years to achieve the limits on NOx whilst the rest of UK industry has to meet these limits now. As with elemental carbon manufacturers and suppliers of plant and equipment are going to take the lead on helping the industry achieve this, it is not something that can be solved easily with ventilation.”
In terms of noise control for people who work on site, Ball says that a good example of the challenges from BS 6164: 2019 is the limit of 80 decibels inside man-riders.
“That is a big challenge for the industry, especially for the manufacturers and the implications on the quality of the rails and impact of external noise such as ventilation system,” he says. “It would be a difficult demand to reach 80 decibels.
Some projects should be able to achieve it but the problem with the noise levels are that they will require big steps in plant design, beyond simply fitting insulation to the transport.” Ball admits that he has spoken with other occupational hygienists about this and some consider it not realistically achievable.
“I agree in part that sometimes it is not achievable, but it will push the industry in improving noise exposures,” says Ball. “Perhaps we won’t be able to take 80 decibels, but will we be able to take 83 decibels? And that would be a big step forward. It’s not the fact we have a limit on one particular part of tunnelling, it is that we are being forced to look at noise control beyond simply providing hearing protection.” A big change that BS 6164:2019 has introduced is the use of monitoring not just to assess safety issues but how to address health issues as well.
“We use the standard to guide us when we consider what monitoring equipment we plan to install from the very early stage of a project,” says Ball. “This has been traditionally concentrated on safety related issues such as oxygen deficiencies or explosive limits. What BS 6164:2019 is now requiring is to consider real time monitoring for health risks such as elemental carbon emissions and dust.”
Occupational hygienists use techniques for collecting and understanding dust levels governed by HSE methodologies.
“These take time and make it difficult to respond immediately to a particular issue,” Ball says. “The requirements for the consideration of real-time monitoring will not only give projects immediate feedback of issues, but they will also give better insight to the cyclical nature of tunnelling processes.”
Ball adds that it will be interesting to see how this requirement for real time monitoring will push the monitoring industry to develop more reliable and accurate equipment. “Real time monitoring for inhalable and respirable fractions of dust at occupational levels is in its infancy at the moment,” he says.
“They don’t really measure inhalable dust levels particularly well. “It would be helpful to know how the improvements of BS 6164:2019 drive the manufacturers of monitoring equipment respond to develop better tools to give us a more reliable and accurate data.”
Future Improvements
Talking about what should be improved in the standard in the future, Ball makes a step back to eight years ago. “If you had asked me that question eight years ago, I wouldn’t have really predicted that the industry would be in the position, for example, to monitor dust levels reliably in real time” he says.
“The equipment was not really manufactured or commonly available, however now manufacturers are seeing a market and are developing products to fill it.”
Thinking in 10 years forward, Ball adds that it’s difficult to predict how scientific research will change the knowledge of what chemicals will do.
“A big change to the tunnelling industry was the classification by the WHO that diesel emissions should be considered a carcinogen. In response to that we are now talking about elemental carbon exposure, monitoring and control, and the BS 6164 is setting the standard of what should be acceptable. As we learn more about what chemicals can do to us we should expect to see BS 6164 and associated guidance change to cater for that.”
“In 10 years, we are likely to see a great requirement for the use of electric plant,” says Ball. “I would expect the electric solution to be a more common place not just from the health perspective, but an environmental one as all industries try to getting greener.”
Ball explains that future versions of BS 6164 will undoubtedly address the need to further minimise the vibration exposure manufacturers through design and methodology. The lower limit for hand arm vibration is 2.5m/s2 and the upper limit is 5mg/sqm.
“I wouldn’t be surprised if the industry finds the exposure limit for hand-arm vibrations reduced in the future,” he says. “Most occupational hygienists are in agreement that even the exposure of 1m/s2 is sufficient for a proportion of population to get vibration white finger.”
Ball believes that with this knowledge they can expect vibration limits to be reduced for the next version of BS 6164, if the legislation isn’t changed first. “Very high vibration exposures occur quickly with operations such as hand mining,” he says.
“It will be extremely difficult to manage these different exposure vibrations levels without help from the design phase and also from plant and tool manufacturers.”
Ball says that another area that they can expect to see changes in the industry is in relation to the fatigue. “Since tunnelling is commonly a 24/7 process fatigue and the impact of shift working is something the industry is increasingly becoming aware of,” says Ball. “BS 6164 would be an ideal source of information to instruct the industry about how this should be managed and what shift patterns can be adopted.”
As overall assessment on the upgrade of the BS6164:2019, Ball gave 8 on the grade scale from 1 to 10.
“I would have given it 9 if there was an improvement in its consideration of vibration as our current limits are too high,” he says. “This should not detract from the significant improvements that BS 6164 has made in addressing the risks of dust and emissions and how we monitor for them.”
“Overall, I am happy that this version of BS 6164 is a step in the right direction with some challenging targets for the industry.”
