High dependency units and intensive therapy units are among the most sensitive areas of any hospital and healthcare bosses need to maintain a high level of cleanliness/hygiene to ensure the safety of staff as well as patients.

Tecomak Environmental Services, who provide HTM 03-01 testing in private and NHS hospitals across the UK, examine the difference between the two types of care, the particular risks for their patients, and how we can ensure that the environment is safe.


Intensive therapy units (ITUs) are also known as intensive care units (ICUs) or critical care units (CCUs). Patients may be in ITUs because:

They need major surgery;

They have a serious infection;

They have recently been involved in a major accident, such as a fall, a fire or a road traffic collision;

They have a serious short-term condition, such as a stroke or a heart attack;

They have major problems with one or more of their organs.

As a result, patients often require the use of monitoring equipment such as ventilators, IV lines and pumps, feeding tubes, drains and catheters. Because they are so ill, there is a low nurse-patient ratio, with every nurse caring for only one or two patients.


High dependency units (HDUs) are also known as also called step-down, progressive or intermediate care units. Some hospitals use them in slightly different ways, or have different criteria for admission, but HDU patients are usually not as unwell as those in ITUs.

HDUs are for people who need more intensive observation, treatment and nursing care than is available in a general ward, but slightly less than that given in intensive care. The patients may be suffering from a problem with a particular organ, such as a liver or kidney, or are recovering from major surgery. Others may have suffered heart problems or respiratory failure and require positive airway pressure ventilation

The nurse-patient ratio is usually slightly higher than an ITU, but lower than a general ward.

What are the Risks?

Whether patients are in an HDU or an ITU, they are still extremely vulnerable to any sort of infection or setback, as their immune system will be less able to fight off so-called ‘superbugs’ such as Clostridioides-Difficile (C-Diff), Methicillin Resistant Staphylococcus Aureus (MRSA) and other infectious diseases.

This means the air in HDUs and ITUs needs to be of the highest possible quality to stop bacteria from spreading, either from other people (such as medical staff) or environmental sources, including surfaces, machinery and equipment. This second category is particularly relevant in ITUs.

Hospitals and other healthcare locations are required to comply with HTM (Health Technical Memorandum) 03-01. This requires that all ventilation systems in these high-risk units must undergo regular and rigorous inspections.

HTM 03-01 Testing from Tecomak Environmental Services

Tecomak Environmental Services provide HTM03-01 testing for all critical ventilation systems in HDUs and ITUs. We have a team of experienced, fully trained teams of engineers who meet all the requirements of the NHS and the Health and Safety Executive.

Our staff check air volumes and air change rates, to ensure the air is flowing correctly and that there aren’t any obstructions – and that air isn’t escaping (or entering) due to a faulty door. They will also check other areas such as the cleanliness of diffusers and pressure stabilisers.

We carry out visual checks every three months, and annual HTM 03-01 verifications. This is all in line with the requirements of the memorandum. If you would like to know more, follow this link and fill in the online form or call us on 01732 852250.