“When applied onto surfaces, antimicrobial coatings inhibit the growth of microbes and disrupts transmission of pathogens from that surface to occupants.”
As the world grapples with the COVID-19 pandemic, the spread of viral and bacterial infections in the built environment has become an even greater public concern. A large number of human illnesses are caused by exposure to bacteria or viruses and aggravated by microbial resistance to antibiotics and disinfectants. Many infections are spread in shared public spaces, prompting design professionals to look at adapting urban design to combat the risk of infection.
Given Australia’s rapidly ageing population, the threat of infectious disease is particularly deadly in this country. Among older Australians, sepsis (organ malfunction caused by infection) claims approximately 5,000 lives every year, with potentially many out-of-hospital deaths unaccounted for.1 This figure outstrips the annual national road toll, and is responsible for more deaths than breast, prostate or colon-rectal cancer.2
Contaminated surfaces provide a potential reservoir for pathogens to persist and spread to humans. Through careful design and specification of antimicrobial surface materials and finishes, the risks of communicable disease can be mitigated within a public or commercial space without compromising on aesthetics, durability and performance.
This whitepaper discusses the health risks associated with contaminated surfaces. We then examine the key considerations when designing healthy and hygienic spaces, with a special focus on surface materials and the benefits of antimicrobial coatings.
INFECTION SPREAD IN BUILT ENVIRONMENTS
In healthcare and aged-care environments, pathogens such as methicillin-resistant Staphylococcus aureus (MRSA), norovirus, influenza virus, Escherichia coli (E.coli) and Clostridium difficile are common.3 These pathogens are shed by patients and staff and can last on surfaces for days, increasing the risk of acquisition. The risk of mortality in these settings is heightened due to the presence of older-age residents or immuno-compromised patients who may be unable to fight off even minor infections.
Regardless of sector, any structure where people are in close-proximity to each other poses an increased risk of infection. This includes high traffic environments such as offices, shopping malls, cruise ships and hotels. For example, gastrointestinal outbreaks are common in cruise ships, spread easily through hand contact of architectural features such as ship railings and bathroom doors.4
In hotels, research shows toilet surfaces, bathroom floors, bathroom sinks, and light switches are potential microbial hazards.5 In a recent study, a hotel bathroom counter was assessed in terms of colony-forming units (CFU) – the number of viable bacteria cells within a sample – and found to have 1,288,817 CFU per square inch.6
Specific indoor environments, such as kitchens and bathrooms have proven to be hot spots for bacterial contamination.7 In these environments, studies show that floors and any surface touched by hands have communities of diverse bacteria.8 Warm and humid conditions, such as those commonly found in bathrooms, provide the ideal setting for the survival of microorganisms.9
Repeated handling increases the risk of contamination – handles, taps, light switches, levers, knobs, and buttons are only a few examples of high-touch surfaces that facilitate the spread of infection. The risk is exacerbated by other factors including poor indoor air quality and inadequate cleaning and maintenance procedures.
Indoor air quality is impacted by the levels of ventilation in a building. Ventilation is critical to cycling out stale air and other pollutants that can adversely impact human health. Insufficient ventilation and poor condensation management can also create elevated building moisture and temperature conditions in which some types of microorganisms can thrive.
Poor choice of cleaning methods and products also contributes to the risk of infection. Some cleaning cloths spread organisms across surfaces rather than removing them. Cleaning equipment is vulnerable to pathogens and can contribute to wider contamination. Surfaces that are difficult to clean, whether they are hard to reach or due to the presence of cracks and crevices, create potential sites for microbial growth.
Designing for Health and Hygiene
A well-designed building fabric – referring to the structural materials, cladding, insulation and finishes that enclose the interior of a building – is in one of the key factors in improving the overall comfort, health and wellbeing of occupants. Buildings codes and regulations set out performance and functionality requirements for the building fabric. The key characteristics are:
- regulates indoor temperatures;
- prevents water penetration and air leakage;
- manages condensation; and
- provides sufficient ventilation.
Bacteria and toxic mould are more likely to thrive in warm and humid conditions, which can be the product of poor ventilation and moisture control. Walls or ceilings that become moist or sticky can have pathogenic microorganisms attaching to them unless they are properly treated with antimicrobial additives or cleaned regularly. Evidence also suggests that low ventilation rates are associated with increased infection rates, especially airborne disease.10
Toxic mould is a contributing factor to “sick building syndrome”, which refers to chronic health issues (e.g. eye and throat irritation, breathing difficulties, allergies, fatigue and headaches) that are linked to time spent in a building.11
Durability refers to a product’s resistance to wear and tear, corrosion, cracking and other damage. Defects on interior surfaces provide areas in which dirt, germs and bacteria can collect. The spaces between cracks on walls, ceilings or other damaged surfaces are prime examples and often overlooked during routine cleaning.
The durability of a product should be matched with its intended purpose. Surfaces that will be subject to heavy traffic or harsh environmental conditions need to be highly durable, and resistant to weather, corrosion or specific chemicals. Temperature fluctuations, such as those experienced in kitchens, manufacturing and industrial settings, also need to be accounted for.
Different materials have different physical characteristics and performance properties. The intended use of the surface and its effect on the material should be considered. Other relevant characteristics include surface hardness, porosity and texture. Materials that are non-toxic and do not release harmful VOCs should be preferred.
Plastic and metals are popular in sanity environments. Stainless steel surfaces are smooth, hard and non-porous, meaning liquid will not seep into the material to create stains or corrosion, but susceptible to scratches which can harbour bacteria if not cleaned properly. Some rigid plastics are porous and need a protective coating to improve their resistance to moisture.12
Wood has known limitations due to issues with porosity and durability that encourage microbial growth and contamination by foreign matter.
Ease of Cleaning
Effective cleaning procedures help reduce illness and maintain safe levels of hygiene in high-traffic environments. Surface materials that are difficult to clean add to operational costs and make it more difficult to maintain a sanitary environment.
When specifying surface materials or finishes for ease-of-cleaning, look for solutions that offer enhanced stain and moisture resistance, self-cleaning features, and are easy-to-wipe. Surfaces that are too rough or textured may be more difficult to clean and thus at risk of harbouring pathogenic microbes. For this reason, smooth surfaces are preferred in sanitary environments.
Cleaning policies and standards vary between sectors. Furthermore, different surface materials require different cleaning and disinfection methods. Some chemicals used for disinfection may damage a surface or destroy any protective coating applied to surface. It is advisable to validate cleaning protocols on the selected surface material to ensure the expected levels of hygiene can be achieved.
Specifying Antimicrobial Coatings
WHAT ARE ANTIMICROBIAL COATINGS?
Antimicrobial coated surfaces offer a high tech solution to minimise the risk of cross-contamination. Antimicrobial coatings contain substances that disrupt bacteria and viruses. When applied onto surfaces, they inhibit the growth of microbes and disrupts transmission of pathogens from that surface to occupants.13
There are several types of antimicrobial surface solutions, each are functionalised using a variety of processes. Some materials are impregnated with bactericides, viral inhibitors and/or fungal inhibitors. Other solutions alter the physical or chemical properties of a surface to create an environment that is harmful to microorganisms. Antimicrobial coatings fall into the latter category, as they typically contain additives or other natural antimicrobial materials (e.g. silver or copper) that are directly applied to a surface leading to a secure, long-term hygienic finish.
Antimicrobial coatings offer a range of health and hygiene benefits. Advanced coating technologies have been scientifically proven to deliver lasting protection against fungi, mould and bacteria, including specific strains of pathogenic microorganisms commonly found in Australia. Some coatings also offer additional resistance to moisture, staining, odours and degradation on the surface on which they are applied.
Utilising antimicrobial coatings throughout a building, and especially on high-touch surfaces, delivers increased levels of cleanliness and hygiene without additional or increased frequency of cleaning. They provide “round-the-clock” protection, minimising the risk of contamination in between cleans, and reducing the presence of germs and bacteria on surfaces.
Leading antimicrobial coatings can be easily incorporated onto most building products and surfaces without compromising the functionality or performance of the product or surface. Permanent architectural features and high-touch surfaces are prime candidates for antimicrobial treatments, including door handles, railings, window frames, floors, and walls linings. Building entrances and foyers should also be considered. Water filters and hoses can be treated to prevent contamination of water supplies from pathogens such as Legionella bacteria.
Not all antimicrobial solutions are the same. Some are effective against only specific pathogens, so the specific health requirements of the space need to be considered. Ensure the antimicrobial solution has been independently tested for effectiveness against harmful pathogens. ISO 22196 provides the testing method to confirm the ability of antimicrobial plastics or other non-porous surfaces to inhibit the growth of microorganisms or kill them over a 24-hour period.
The coating must also be fit for purpose. This means determining whether the surface, after the coating has been applied, delivers the required levels of durability for the intended use. New building work in Australia must also comply with the performance requirements in the National Construction Code and related Australian Standards. Accordingly, other performance considerations such as acoustics and fire resistance are also relevant when specifying antimicrobial coatings.
Keystone Linings supplies architects, interior designers and builders with premium quality, high performance linings and acoustic solutions for interior walls, ceilings, exterior facades and soffits. Showcased in many of Australia’s iconic buildings, Keystone combine the widest range of quality substrates with the latest in innovative finishes to deliver acoustic performance, durability and design versatility.
Keystone engineer panels to suit diverse applications – from contemporary office fitouts to exemplary facades. The company’s architectural consultants and project managers work closely with design and construction professionals to develop the best solution for any given project.
KEY-GUARD – ANTIMICROBIAL COATING
Key-Guard is an antimicrobial surface coating formulated by Keystone Linings in partnership with British antimicrobial experts, Biomaster that can be applied to wall and ceiling linings as well as various surfaces to provide a protective finish and reduce bacterial transfer. Recommended for environments where hygiene is critical including healthcare, hospitality, retail and education, Key-Guard is an excellent addition to any project, ensuring peace of mind without the need for regular cleaning.
Features and benefits:
- Includes the Biomaster additive for round-the-clock antibacterial protection
- Independently tested for antimicrobial efficiency
- Hard wearing, durable, premium polyurethane coating system
- Available in a range of gloss levels and can be tinted to a comprehensive range of colours
Biomaster pioneered the use of silver-based antimicrobial additives and today is the recognised leader in antimicrobial technology. The Biomaster additive also contains Verimaster security technology, a covert identification system designed to verify the presence of the active antimicrobial ingredient.
In typical tests, after 24 hours surfaces treated with Biomaster showed a reduction in the levels of E.coli and Staphylococcus aureus by over 99% achieving ISO 22196:2011. When incorporated into architectural solutions, Biomaster provides effective antimicrobial protection for the lifetime of the product.
1 Australian Institute of Health and Welfare. “Older Australia at a glance.” AIHW.
https://www.aihw.gov.au/reports/older-people/older-australia-at-a-glance/contents/demographics-of-older-australians (accessed 28 September 2020).
3 Dancer, Stephanie. “Controlling Hospital-Acquired Infection: Focus on the Role of the Environment and New Technologies for Decontamination.”
Clinical Microbiology Reviews Vol. 24, Issue 4 (2014): 665-690.
4 Dell’Amore, Christine. “Cruise Ship Illness: Why Are Ships So Prone to Norovirus Outbreaks?” National Geographic.
https://www.nationalgeographic.com/news/2014/1/140128-cruise-ship-royal-caribbean-nation-health-science-virus (accessed 28 September 2020).
5 Almanza, Barbara, Katie Kirsch, Sheryl Fried Kline, Sujata Sirsat, Olivia Stroia, Jin Kyung Choi and Jay Neal. “How Clean Are Hotel Rooms? Part I: Visual Observations vs. Microbiological Contamination.” Journal of Environmental Health Vol. 78, No. 1 (2015): 8-13.
6 TravelMath. “Hotel Hygiene Exposed.” TravelMath. https://www.travelmath.com/feature/hotel-hygiene-exposed (accessed 28 September 2020).
7 Flores, Gilberto E., Scott T. Bates, Dan Knights, Christian L. Lauber, Jesse Stombaugh, Rob Knight and Noah Fierer. “Microbial Biogeography of Public Restroom Surfaces.” PlosOne. https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0028132 (accessed 28 September 2020).
9 Suen, Lorna K. P., Gilman K. H. Siu, Yue Ping Guo, Simon K. W. Yeung, Kiki Y. K. Lo and Margaret O’Donoghue. “The public washroom – friend or foe? An observational study of washroom cleanliness combined with microbiological investigation of hand hygiene facilities.” Antimicrobial Resistance and Infection Control Vol. 8, Issue 47 (2019): https://aricjournal.biomedcentral.com/articles/10.1186/s13756-019-0500-z (accessed 28 September 2020).
10 James Atkinson, Yves Chartier, Carmen Lúcia Pessoa-Silva, Paul Jensen, Yuguo Li and Wing-Hong Seto. “Natural ventilation for infection control in health-care settings: WHO guidelines 2009.” WHO. https://www.who.int/water_sanitation_health/publications/natural_ventilation/en (accessed 28 September 2020).
11 Joshi, Sumedha M. “The sick building syndrome.” Indian Journal of Occupational & Environmental Medicine Vol. 12, No. 2 (2008): 61-64.
12 Lybert, Lynda. “Porous and nonporous hard surfaces: Determining the best material for health care applications.” Health Facilities Management Magazine.
https://www.hfmmagazine.com/articles/2274-porous-and-nonporous-hard-surfaces (accessed 28 September 2020).
13 Above n 3.
All information provided correct as of October 2020