Healthcare-associated infections (HCAI) affect 5-10% of patients admitted to an acute hospital but it is about three times higher in intensive care units (ICUs). Prevention involves many strategies but environmental hygiene is important as many bacterial causes persist on horizontal surfaces, e.g. methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE) and Clostridium difficile. Conventional approaches to hospital cleaning including the use of detergents and disinfectants are often inadequate because of poor practice, difficulties in accessing busy clinical areas, and challenges in decontaminating items that are heat sensitive. Cold air plasma is an emerging approach which can reduce the numbers of viable bacteria on a surface by a factor of 100, or more, and has been piloted in Beaumont Hospital. We propose to carry out a controlled study which would use cold air plasma, in addition to conventional hospital cleaning to: decrease the overall numbers of all bacteria on high risk or commonly touched surfaces in two ICUs and numbers of VRE and C. difficile. At the same time, we will also monitor the quality of routine cleaning using a well proven method. A second objective will be to reduce the acquisition of VRE and C. difficile infection amongst patients admitted to the two ICUs. ‘High risk’ surfaces that are frequently in contact with the patient, e.g. bed sides, will be targeted by the cold air plasma decontamination process. This study will be carried out in a clinical arena, but with no danger to patients or staff, and will confirm the usefulness of this novel decontamination approach in improving hospital hygiene, reducing surface bacterial numbers and preventing HCAI.