Taxpayers will buy millions of dollars worth of nicotine substitutes as South Australia makes its jails smoke-free.

Nicotine patches and lozenges are included in a $6.2 million effort to remove cigarettes from the state's prisons by 2022, which will also cover health and security measures, staff costs and quit support.

The smoking ban is supported by Cancer Council SA and the Public Service Association, which represents the state's prison guards.

Under the new rules, taxpayers will foot the bill for the first six weeks of a nicotine replacement program, with prisoners required to pay a quarter for the next three weeks and half for the final three weeks.

Estimates suggest up to 80 per cent of South Australia's 2,800 prisoner population smokes, with 75 per cent smoking daily.

Currently, they can buy their own cigarettes and tobacco from the prison canteen.

Public Service Association SA general secretary Nev Kitchin said the union has been calling for a smoking ban for years.

“We believe the department has probably been in breach of work health and safety regulations,” Mr Kitchin said.

“No-one should be required to work in an environment with smoke in it.

“We are looking for the bans to be introduced in a structured way.”

Cancer Council SA spokeswoman Alana Sparrow said the SA Government had come up with a “good evidence-based approach”.

“We have looked at evaluations in different states and territories — in some it has worked extremely well but we are also learning from the experiences in other states like Victoria,” Ms Sparrow said.

Smoking is already banned in prisons in New South Wales, the Northern Territory, Tasmania, Victoria and Queensland.