Corrective Services NSW has defended a loophole that allows prison staff who live on-site to smoke in designated areas once a smoking ban becomes effective.

NSW prisons will become smoke-free zones on Monday, but staff who live on CSNSW sites will be able to smoke while off-duty.

A spokesman says they will smoke only in designated areas not visible from a correctional centre, with most of the sites in remote locations such as Ivanhoe and Brewarinna.

"Staff pay rent for this accommodation and it is not considered their workplace," CSNSW said in a statement.

Meanwhile, staff have been bracing for riots over the ban, and emergency management plans are in place.

In NSW, about 76 per cent of inmates smoke, compared with about 17 per cent of the general population, according to healthcare prison provider Justice Health & Forensic Mental Health Network.

"About 85 per cent of inmates who smoke have told us they would like to quit, but the prevalence of smoking in prisons makes it hard," JH&FMHN chief executive Julie Babineau said.