Nearly 40 people have either escaped or wandered off from The Dales Unit at Calderdale Royal Hospital this year.
And between January 1 2008 up until September 20 this year the figure stood at 235 people who had been sectioned under the mental health act had left the Halifax hospital.
The figures were released under the Freedom of Information Act and identify why West Yorkshire Police has concerns in respect of potential issues of public safety.
South West Yorkshire Partnership NHS Foundation Trust is responsible for the unit and has now applied for planning permission for the smoking area at the hospital to be protected by fencing to prevent patients escaping.
The application says: “The need to upgrade the security of the facility has arisen from an increase in the number of absconsions from the site and is intended to address the concerns of West Yorkshire Police in respect of potential issues of public safety.”
If successful a new 3.6m wire fence - a metre higher than current fencing - will be constructed.
The smoking area will also get new bedding areas for plants and a central parasol area with seating at the heart of the garden.
There will also be a ‘Zen garden’ beyond formed in resin bonded gravel and incorporating large rocks and a water feature for mental stimulation and relaxation.
The figures revealed the following: in 2008 71 people escaped or wandered off, for 2009 it was 35 and in 2010 only 12.
This figure slightly rose in 2011 with 21 people and in 2012 it was 60 people.