Extremely high concentrations of airborne fungi regarded as a potential "health risk to all persons" have been found in the M4 East tunnels under construction in Sydney's inner west.
The findings prompted about 500 construction workers to walk off the job on Friday, saying they had failed to receive adequate assurances from the contractor building the twin 5.5-kilometre tunnels from Homebush to Haberfield that their health would be safe.
A confidential report, completed on Monday by a Mycolab laboratory, found the average of four samples taken from inside the tunnels had a rating of "extremely high" airborne fungal concentrations. The tunnels will form the first stage of the $16.8 billion WestConnex toll road.
High concentrations of airborne fungi have been found in the M4 East tunnels.Credit: Steven Siewert
"This [airborne concentration] was significantly higher than the outdoor airborne fungal concentrations," the report said.
"The indoor locations tested had 'elevated to extremely high' levels."
The report, which was commissioned by construction company CPB Contractors, said extremely high fungal concentrations in the air could have "probable health risk to all persons". Elevated or high levels can also pose a "health risk to sensitised individuals", it said.
Electricians and other construction staff refused to enter the tunnels on the M4 East project on Friday morning, calling for CPB Contractors to take steps to safeguard their health. They later walked off the site.
The Electrical Trades Union, which represents hundreds of electricians and plumbers working on the M4 East, said concerns about high levels of fungi in the tunnels due to inadequate ventilation had been raised on a number of occasions with CPB Contractors by workers who had prolonged exposure to the contamination.
"We believe there is an ongoing and imminent risk to people's health and safety," ETU organiser Stewart Edward said. "[Workers] are very frustrated. We raised concerns last Friday and we asked for an independent hygienist to come in."
The report by Mycolab also found samples taken from surfaces at the construction site showed all five locations tested had "extreme contamination" levels of mould concentrations.
A WestConnex spokeswoman said the contractor had put in place a number of "precautionary measures" to ensure the site remained safe. "These include further testing, compulsory masks for all tunnel workers while additional testing takes place and additional cleaning of all facilities. Additional ventilation has been introduced in some areas of the tunnels," she said.
NSW Treasurer Dominic Perrottet urged all workers to return to the work site and “get on with the job”, saying SafeWork had concluded it was “acceptable”.
Asked whether the union was playing political games, he said: “We are working closely with the unions; we’ve been the best thing for them because we’re building $90 billion worth of infrastructure."
The state government has said it expects the M4 East, the first major part of WestConnex and costing $3.8 billion to build, to open to motorists within the next three months.
WestConnex said on Friday that the higher levels of airborne fungal spores detected in "limited unventilated areas" would not impact on the timeline for construction of the M4 East or on motorists using the tunnels when they open.
CPB Contractors declined to comment on the matter.
With Esther Han