Many prisoners would consider it tougher to get through the day without a cigarette than spend their nights behind bars - but at one prison that is now the new reality.
The Tung Tau Correctional Institution at Stanley is the city's first non-smoking prison, the latest bid to end smoking in jails.
But the Correctional Services Department says smokers will not be forced to give up - those determined to continue will be sent elsewhere, while those who want to quit will be given counselling and support.
Smoking has been banned in most indoor public spaces since 2007. Prisons have adapted by installing ventilated smoking booths in workshops and dormitories. The department also encourages and supports inmates to give up smoking through education, counselling and quit courses.
Tung Tau, a minimum-security institution opened in 1982, first trialled a no-smoking zone in 2011 to encourage inmates to give up and clear the air for non-smokers.
There are no plans to extend the ban, but quit programmes and nicotine replacement therapy have been trialled at Stanley Prison and Lo Wu Correctional Institution.
"All inmates eventually committed to stop buying cigarettes and smoking," a department spokesman said.
But bans on smoking in prisons have not proved popular elsewhere in the world.
Britain was to implement its first smoking ban at Exeter Prison in March, but postponed it because of fears it would spark an uproar among inmates.
British authorities now hope to implement the ban within the next two years, with prisoners given nicotine patches or electronic cigarettes.
Smoking in British jails has been restricted since the general ban in enclosed public places came into force in 2007, but inmates can smoke in their own cell because they have been designated "their permanent or temporary home".