Safe Surfacing

“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

RISK FACTORS

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.

SURFACE PROPERTIES

Durability

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.

Material Selection

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.

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.

BENEFITS

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.

DESIGN APPLICATIONS

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.