Scotland's largest health board is to allow the use of electronic cigarettes within its hospital grounds.
Tobacco smoking was banned in all health grounds in Scotland in April, but health boards were given discretion over the use of vaping devices.
NHS Lothian was the only one of the 13 health boards at the time to allow restricted use of e-cigarettes.
NHS Greater Glasgow and Clyde has said it will do so too, after new evidence that they help tackle tobacco smoking.
Dr Emilia Crighton, NHS GGC's director of public health, said: "It is clear from research carried out by Public Health England, ourselves and others, that e-cigarettes do have their place in the fight against tobacco and are being used effectively to help people stop smoking altogether.
"In NHS GGC we have carried out our own research which has revealed that some 32% of smokers in our health board area intend to use e-cigarettes in their next quit attempt and that 18% of recent ex-smokers used them to help give up tobacco in the past 12 months.
"It is therefore very important that we organise our services to ensure that that we can safely and effectively manage the use e-cigarettes as part of suite of services to help people give up tobacco."
The health board said its policy change was "consistent with guidance recently published by Health Scotland which recommends that NHS smoking cessation services should support those choosing to quit smoking by using e-cigarettes".
It is also considered that the use e-cigarettes would be helpful in the context of supporting mental health sites to become completely tobacco free.
Dr Crighton added: "We know that the smoking rate is particularly high amongst people with mental health problems and we are of the view that the use of e-cigarettes on our sites will allow us to be able to provide particular support to this group of patients by re-designating traditional smoking areas for the use of e-cigarettes."
NHS GGC said it would now identify specific areas within hospital grounds and other healthcare facilities where e-cigarettes would be permitted.
Staff, patients and visitors would then be informed that tobacco and e-cigarettes were treated differently with information provided on where e-cigarettes could be used.