ACCORDING TO BOHS, the Chartered Society for Worker Health Protection, every year in the UK about 13,000 people die from work-related diseases, and in the construction industry the incidence is particularly high.
Construction workers in the UK are 100 times more likely to die from an occupational disease than a workplace accident. This is illustrated by the fact that in 2014/15 there were 35 fatal injuries to UK construction workers whereas over the same period in the industry there were around 5,500 new occupational cancer cases, 3,500 deaths from past exposures to asbestos and 500 deaths from exposure to silica dust. There are perhaps few harsher construction environments than a tunnel. Standard practice to ensure that Permitted Exposure Levels are not exceeded is for operatives to wear personal monitors but these only reveal retrospectively what the worker has been exposed to. If dust exposure levels need to be assessed the data from the monitors has to be analysed by an external laboratory and there’s a lengthy wait for results.
Now British company Trolex is changing the game with a real-time respirable dust monitor – the Trolex TX8001. The company has already supplied gas monitors to Crossrail sites, where the devices are placed every 500m, and it is now trialling its new dust monitor during construction of the new Liverpool Street Crossrail station, where Laing O’Rourke has the contract for the main construction works.
The fi rst dust monitor was installed 17 months ago in the Blomfi eld box, a 40m-deep shaft which will accommodate ventilation, electrical, mechanical and systems equipment for the new station. Trolex has made changes to the monitor during the trial and there is now one in each of the two tunnels at the station. One is not fi xed so it can be moved to areas where work is generating dust.
“It’s done away with personal dust monitors which are used on other Crossrail sites,” said Dean Bonvini, senior construction manager at Laing O’Rourke. The robust, sealed unit provides real-time particle counting of respirable dust, which is not visible to the eye, and produces the results instantly, alerting operatives to immediate risk and negating the need for costly and time-consuming laboratory analysis. The monitor, which is linked to the site offi ce via an ethernet cable, displays the 15-minute and eight-hour time- weighted average. As it is an open flow device there is no need for filters or pumps and there are no moving parts or consumables.
“In the past we would have used personal monitors and had to have waited three weeks for the results of the readings,” said Bonvini. “With this it’s instant; it’s a live reading.”
Trolex says the TX8001 is accurate to within +/-5% compared with +/-25% for the current industry standard model. It operates in the 1 to 10 micron respirable fraction particle range and in the event of dust concentration exceeding the upper limit, the monitor has an in-built alarm. Since it was installed at Liverpool Street, however, the alarm has never been activated. “The results have been pretty good,” said Bonvini.
Since the trial began 17 months ago Trolex has made changes to the monitor in response to Laing O’Rourke’s experience with the device.
“We’re on Mark III now and it will pretty much be the final spec,” said Trolex business manager Mark Bennett. The final product will be integrated with Trolex’s gas monitoring systems and also include a visual indicator so site workers can easily see changes in respirable dust levels.
Bonvini said the visual display provided reassurance to operatives that they were working in a safe environment and Laing O’Rourke would be recommending the monitor’s use for other Crossrail sites. “It provides reassurance. We are always looking for new and exciting developments in the construction industry and we have confidence in it,” he said.
Trolex is also pleased with the monitor’s performance during the trial and Bennett believes it has huge potential, not just in the construction industry.
“I think it could very well become the industry standard for all dusty work sites, whether that’s a tunnel, a sawmill or in the pharmaceuticals industry,” he said