Crossrail workers are demanding an investigation after five colleagues working at Bond Street station allegedly died in their sleep over the past six months.
However, a spokesperson for the company stated that only three workers have died since June, adding that a fourth died earlier this year from an unrelated illness.
The other two died in their sleep last Saturday and Monday, prompting fears over dust and oxygen levels in the underground site.
It is not clear exactly what has led to the deaths, but many employees downed tools earlier this week in protest against working conditions.
The two most recent deaths were both the result of suspected heart attacks.
A member of staff told Metro.co.uk: ‘You’re talking about reasonably healthy people, good health.
‘No one is happy. A lot of people knew the guys, it’s not a nice environment on site at the moment.
‘Everyone’s at each other’s throats. Management are clearly more interested in making sure that it doesn’t get out, really they are trying to keep everything quiet.’
He said everyone who has died have all been contractors from different companies, suggesting their premature deaths could be related to the site itself.
A source has said dust monitor tests on site in recent months have been frequently showing red.
He said poor ventilation, working five levels below ground and drilling and cutting wood is a potentially dangerous combination.
Commenting on the man who died on Saturday night, the source added: ‘Lack of sunshine, no real fresh air, he works on level minus five. I’ve got a sort of inkling that this is what it is.’
After learning of their colleague’s death at a briefing on Monday morning, many workers reportedly refused to work.
They spent two days in an above ground staffing area on Monday and Tuesday but have since gone back to work with dust masks on.
The source added: ‘At the end of the day if you’re wearing a dust mask there’s a problem.’
It is understood that the issue has been raised with the main contractor Costain Skanska Joint Venture (CSJV) and that another company has been brought in to test dust levels.
A spokesperson for CSJV said: ‘Our condolences go out to the friends, families and colleagues of those who have recently passed away.
‘The safety of all colleagues working at CSJV sites is absolutely paramount. Independent air quality monitoring at Bond Street is conducted at regular intervals as well as for specific planned construction activities.
‘This monitoring has never revealed anything concerning or unexpected. Any concerns raised about health and safety on site will always be fully investigated with the appropriate action always taken.’
A spokesperson for Crossrail Ltd said their thoughts were with colleagues at Bond Street and the friends and families of those who died.
They continued: ‘Crossrail Ltd demands the highest standards of health and safety across the project and we continue to work closely with our Bond Street contractor Costain Skanska Joint Venture in support of making sure this is the case.
‘Crossrail and its contractors monitor the air quality at all sites to ensure that compliance requirements are met and that workers are not exposed to unacceptable levels of dust.’