"Inmates are breathing easy following the prison smoking ban with scientists finding a greater than 50 per cent rise in air quality and – to everyone's surprise – no major incidents since the big stub out.
Smoking was banned in New Zealand prisons on June 1 last year with stark warnings from prisoners, prison advocates, and guards of riots and disorder.
However, there were no riots and Corrections staff report a number of unforeseen benefits..."
The smoking ban is probably quite a deterrant to many- probably the most powerful one...