The microbiologist who inspected mouldy facilities at the Nauru detention centre became sick after he was told he couldn't wear his protective goggles and suit for fear of inciting a riot among asylum seekers.
Then-detention centre operator Transfield (now Broadspectrum) commissioned Cameron Jones to travel to Nauru in October 2014 to conduct on-site scientific tests in the tents and new modular buildings.
Dr Jones has now broken his silence about his time on Nauru.
"I was prohibited from wearing personal protective equipment by Transfield due to what they thought was a foreseeable risk of inciting a riot," he told AAP, adding he wasn't allowed to wear his usual plastic suit, goggles and full face mask.
"I myself became unwell after the inspections ... I had gastrointestinal problems and long-term sinus issues."
Following a 15 month investigation, AAP obtained a leaked copy of Dr Jones' 247-page report which warned Transfield and the immigration department (now Home Affairs) of the mould health risks.
It warned airborne and surface-bound fungal and bacterial cells and spores are capable of causing disease "by direct infection, toxicosis or by allergy".
AAP is aware of at least 20 former detention centre staff who have become seriously ill from mould exposure, including an Australian teacher who now has a cognitive disability which affects her speech and memory.
Dr Jones characterised the smell of mould at the centre as "enough to illicit an immune response".
"It's like being next to a compost heap all the time," he said.
After finishing his testing at the centre, Dr Jones had a debriefing with Transfield about his findings and was told there was $3.2 million a year available for fixing the mould problem.
He said senior personnel at Transfield appeared extremely willing to do something about the problem and he had left Nauru on positive terms.
But the tide turned once he submitted his report about a month later and he had to fight for several weeks to get Transfield to pay him.
"Once they had the report (of) exposure risks to mould spores, cell wall fragments, mycotoxins, I think the evidence became so compelling that it was easier to deny its existence," he said.
Dr Jones said security guards at the detention centre had prevented him from taking extensive photographs and video to capture the scale of the mould problem.
"I had to show my camera every day to the guards who then went through all the photographs," he said.
Broadspectrum insists it maintained a safe and healthy workplace for its employees while working at the detention centre until late October 2017.
The Home Affairs Department denied there had been any illnesses as a result of mould exposure at the Nauru detention centre.
However, Comcare told AAP it received a complaint in 2016 from a worker employed by a contractor, who had been diagnosed with a respiratory condition after living at the Nauru detention centre.