The health and safety watchdog has ordered bosses at a Glasgow hospital to make improvements.
Greater Glasgow health board confirmed it received an improvement notice from the Health and Safety Executive (HSE) on Christmas Eve.
The notice states the hospital has failed to ensure the ventilation system within a ward at the Queen Elizabeth University Hospital is suitable.
A meeting has been set up between the board and HSE to discuss the notice.
It states that the hospital has failed to ensure the ventilation system within Ward 4C is "suitable and sufficient to ensure that high risk patients who are vulnerable to infection are protected from exposure to potentially harmful airborne microbiological organisms".
As part of the notice the hospital will be required to carry out a verification of the ventilation system for Ward 4C, a renal transplant/haemato-oncology ward, by 31 March 2020.
'Sorry for the distress'
NHS GGC chief executive Jane Grant said: "We are sorry for the distress that patients and their families have experienced by the current issues and want to assure them and the public that we are working with the Scottish government to do everything necessary to remedy the situation."
She continued: "Patients who require specialist ventilation are cared for in Ward 4B which is a fully HEPA-filtered ward.
"As a further precaution we introduced mobile HEPA filters in Ward 4C in January as part of our control measures when we were investigating infections at that time.
"We welcome the opportunity to discuss these actions with the Health and Safety Executive when we meet them in the new year."
The improvement notice comes after NHS GGC was escalated to stage four of the NHS Board Performance Framework by Health Secretary Jeane Freeman - the second highest level of Scottish government intervention - in November following its response to infection control.
Concerns about the water supply at the hospital were raised after it emerged 10-year-old cancer patient Milly Main died after contracting an infection in August 2017.
A Scottish government spokeswoman said: "We are aware that NHS Greater Glasgow and Clyde has received a notification of contravention letter and an improvement notice from the Health and Safety Executive.
"We have been clear that we expect the board to address any identified breaches as a matter of urgency and provide detailed evidence to demonstrate that remedial action has been taken."