INFECTION PREVENTION


therefore also be used to determine which areas of a surface should be swabbed for culture, as the most heavily contaminated areas above 2,500 APs are probably the areas that will get a culture result. Whilst we can only estimate the viral load in air samples (by particulate size), it is almost certain that during the year there will have been changes in dominant airborne viruses. From student sickness reporting, these included influenza, coronaviruses and norovirus. It appears that the viral load had litle or no effect on bacterial counts. Although this is not proven, it can be stated that they had no effect on the ratio of bacterial CFU to APs in the 0.5-1 micron range. The UN/WHO indoor air quality


standards commitee need to take these results into account before producing their indoor air quality standards. Any standard that does not allow for the use of antimicrobials, using only CO2


It is now possible to use a simple air particle sampler 20 cm above a surface to get a reading accurate enough to approximate surface contamination in just a few minutes


culture swab is likely to produce a result, and as it is clear from the study that there are disinfection products that will result in counts lower than that. Until more is known, it is the authors’ opinion that this would be the ideal point at which swabs should be taken, and recleaning/ disinfection of the surfaces should take place.


levels for


guidance, will almost certainly not reflect the true levels of contamination and therefore potential for harm in any room.


Authors’ comment It is now the authors’ view that whilst air sampling will not give an indication of bacterial species colonising surfaces, as it does not satisfy all the ideal test criteria, it could be adopted as a fast, accurate, simple, inexpensive and effective way to determine approximate contamination levels, until results of culture are known. At the very least, using air sampling to identify areas of highest levels of contamination will improve the possibility of geting a result from culture or PCR. Whilst accurate and approximate are used in the same sentence and would appear to contradict each other, in practical terms, the test is accurate enough to give confidence that the approximate contamination level on a surface needs atention, or not. There is clearly still a decision to be


made over acceptable levels of APs and surface counts. We know from studies that some pathogens like E. coli and norovirus, require only very low levels of contamination to become a potential problem for staff and patients.5


Further


study is needed to understand at what levels surfaces become a danger in respect to cross infection potential, but the methodology will almost certainly need to include more specificity on species identification. Until a new more accurate test method that meets all the criteria mentioned in this paper is developed, there will still be the potential for cross contamination from surfaces. As the results show an air sampling total count of approximately 2,500 particles/ 75 CFU per cm2


, is the break point at which a


References 1 Kemp A, Hanson D. Is There a Measurable


Relationship Between Air and Surface Contamination? Study Of Student Classrooms and Sports Facilities at the University of Surrey, UK. Am J Biomed Sci & Res. 2026;29(5):780-785. doi:10.34297/ AJBSR.2026.29.003850


2 Kemp A. A new era in bacterial detection for healthcare? Clinical Services Journal 2018 October;17(9): 38-39


3 Iwamura N, Tsutsumi K, Hamashoji T, Arita Y, Deguchi T. Carbon Dioxide Levels as a Key Indicator for Managing SARS-CoV-2 Airborne Transmission Risks Across 10 Indoor Scenarios. Cureus. 2024;16(11):e74429. doi:10.7759/cureus.74429


4 Boone SA, Gerba CP. Significance of fomites in the spread of respiratory and enteric viral disease. Appl Environ Microbiol. 2007;73(6):1687-1696. doi:10.1128/AEM.02051-06


5 Oter JA, Yezli S, Salkeld JA, French GL. Evidence that contaminated surfaces contribute to the transmission of hospital pathogens and an overview of strategies to address contaminated surfaces in hospital setings. Am J Infect Control. 2013;41(5 Suppl):S6-S11. doi:10.1016/j.ajic.2012.12.004


6 Wand ME, Bock LJ, Bonney LC, Suton JM. Mechanisms of Increased Resistance to Chlorhexidine and Cross-Resistance to Colistin following Exposure of Klebsiella pneumoniae Clinical Isolates to Chlorhexidine. Antimicrob Agents Chemother. 2016;61(1):e01162-16. doi:10.1128/ AAC.01162-16


7 van der Schoor AS, Boyle M, Voor In ‘t Holt AF, Vos MC, Humphreys H; ESCMID Study Group for Nosocomial Infections. Environmental sampling of innate hospital surfaces: a survey of current practices and the need for guidelines. J Hosp Infect. 2022;128:92-95. doi:10.1016/j.jhin.2022.07.024


8 Kemp A, Diggle M, Baird K. Guidance standards for establishing and assessing


34 WWW.PATHOLOGYINPRACTICE.COM April 2026


cleaning and disinfection in UK Hospitals and other healthcare facilities. (BICSc, 2020) www.bics.org.uk/cleaning-disinfection- quality-guidance-standards-with-dr- andrew-kemp-phd-dr-mathew-diggle-frcp- dr-katie-laird-phd/


PPi


9 NHS England. National Standards of Healthcare Cleanliness 2025. (NHSE, 2025) www.england.nhs.uk/estates/national- standards-of-healthcare-cleanliness/


10 NHS England. Health Technical Memorandum 03-01: Specialised ventilation for healthcare premises. (NHSE, 2024). www. england.nhs.uk/publication/specialised- ventilation-for-healthcare-buildings/


11 Kemp A, Diggle M. How Do We Clean Up This Mess? – A Review of The Testing Methodologies Used for Detection of Live Bacteria in Healthcare Environments. Am J Biomed Sci & Res. 2019;4(4):244- 248 doi:10.34297/AJBSR.2019.04.000808


12 Kemp A, Hodgkinson V. Comparing air and surface contamination levels with new disinfection methods. Pathology in Practice 2024 December;28(8):41-44.


13 Murray PR, Baron EJ, Jorgensen JH, Landry ML, Pfaller MA, eds. Manual of clinical microbiology. 9th edn. Washington DC: ASM Press, 2007


14 Bollmann A, Lewis K, Epstein SS. Incubation of environmental samples in a diffusion chamber increases the diversity of recovered isolates. Appl Environ Microbiol. 2007;73(20):6386-6390. doi:10.1128/ AEM.01309-07


15 Kemp A. Antimicrobial Efficacy and Lack of Resistance to Silane Quaternary Compounds. Pathology in Practice 2020 April;21(2):23-28.


Andrew Kemp, JP, PhD, Head of Scientific Advisory Board, British Institute of Cleaning Science, UK Antimicrobial Resistance Ambassador, AMR insights Amsterdam. Denise Hanson FBICSc, Director of Training, British Institute of Cleaning Science, Moulton Park, Northampton UK.


This research was funded entirely by the British Institute of Cleaning Science (BISc) and the Cleaning and Support Services Association (CSSA) with products and services provided for free by the relevant parties. At the time of publication there are no conflicts of interest.


British Institute of Cleaning Science www.bics.org.uk


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