Pretoria - Workers at the National Department of Health's Civitas building on Thabo Sehume Street protested against the "unsafe conditions" at the offices' main entrance on Tuesday.
They vowed that they won't resume work until Health Minister Aaron Motsoaledi had addressed their complaints about the unsafe working environment.
They also blamed the minister for the death of their colleague Caroline Nkosi, who passed away last week after she experienced breathing difficulties.
Nkosi's death was reported after she collapsed while at work on Novemver 12 last year.
Demonstrators said Nkosi had a respiratory problem, which was allegedly caused by the dust conditions at work.
The Nkosi family also believed that their daughter died as a result of the unsafe conditions inside the Civitas building.
They wanted answers from the department as to why Nkosi was allowed to work in such poor conditions.
Nehawu representative Bhungani Mzolo said the unsafe conditions at the building were confirmed by a report compiled by the Department of Labour.
He said the report was compiled following an inspection on November 29 2018.
Mzolo said workers wanted the minister and the director-general to make sure that the building complied with the occupational health and safety Act.
"The building must be in a such a condition that the employees are able to work, where they can be able to breath and where they don't suffer from diseases," he said.
He said workers were not on strike, but were there "to agitate and make sure that we get the authority to comply with the Act".
He said the longstanding complaints by workers were confirmed by a report compiled by the Labour Department following an inspection of the building on November 29 last year.
The report, dated January 15, 2019, noted that the inspection established "that there is a presence of black dust in every office we have inspected, both in the south tower and north tower".
According to the report, the dust was found on windows, walls around air-conditioning units and inside the air-conditioning unit grid covers.
"Employees that were interviewed claim that they experience traces of a black substance when they blow their nose," the report said.
Department spokesperson Popo Maja said he was not in a position to comment because he was in a meeting.