The Role of Architectural Coatings in Creating Healthier Indoor Environments

No one in the architectural coatings industry needs to be told that their work is a constant balancing act between providing a high-quality product that manages to surpass that of competitors; to service regulatory demands and aspirational goals for more sustainable products; and to keep prices as consistent as possible for the end user.

Supply chain and logistical challenges of the last few years have not helped. And there is increasing pressure to move towards more sustainable manufacturing practices. Interest is growing in looking through a wider ESG lens at all products and services, at the companies that provide them, and at the people who are impacted by their manufacture and use. 

ESG of course stands for Environmental, Social and Governance, and it’s a framework that looks at how a company operates to support the planet and its people, under the broader umbrella of sustainability.

And while there are very valid reasons for  acting on social imperatives such as the climate crisis and looking to make products healthier for those who use them, that doesn’t mean that making these changes is easy! Nor is it easy to communicate those changes to end customers. 

In this article we’re going to run through some key developments in coatings that relate to human health and broader sustainability, and that are getting more attention both in the industry and in the general public. The industry is moving towards removing some elements such as PFAS and certain biocides. At the same time, the introduction of other innovations such as photocatalytic ‘air-cleaning’ technology, anti-microbials, and bio-based elements are all aimed at contributing to human health but in very different ways. We’ll then talk about pulling those together into systems that make sense to the design community and to the general public.

PFAS stands for per- and polyfluoroalkyl substances, and they are a class of chemicals used widely across many industries. They are sometimes referred to as ‘forever chemicals’ because they persist for such a long time in the environment. They have negative human health impacts, and can build up in human tissues. Ironically, their great stability is what leads to them being used in consumer products, and it is partly this stability which causes their persistence in the environment. Last year the Healthy Building Network¹ tested a range of paints for markers of PFAS, and found that 50% of the samples they tested were positive. 

Regulation has already started to be put in place around PFAS in some classes of products. And in the USA, California is leading the charge, as it often does. Limits on PFAS in general, and bans on ‘intentionally added’ PFAS are being introduced for product classes such as apparel, cookware, food packaging, and cosmetics. Paint will likely be in line for regulation in due course, and wise manufacturers are already leading the charge in removing PFAS from their products, starting with intentionally added PFAS. 

Biocides have been an area of interest for some years now, and many jurisdictions have in particular turned their attention to isothiazolinones such as MIT, CMIT etc. It is well-established that the presence of isothiazolinones  as a preservative in cosmetic and non-cosmetic products have caused sensitization and contact dermatitis, even at very low concentrations². The European Union has placed limits on the worst offenders for use in cosmetics, and many coatings are required to carry an allergy warning. 

Since the recent pandemic there has been a rise in the number of coatings using anti-microbial agents such as silver ions, copper, or zinc, which are known for their ability to inhibit the growth of bacteria, fungi and other pathogens. Photocatalytic technologies use compounds like titanium dioxide that react with light to break down pollutants and harmful chemicals in the air. Whereas in the case of PFAS and isothiazolinones, the industry is moving towards removing or reducing these to contribute to healthier outcomes, anti-microbial agents and photocatalytic technologies take an additive approach to improving the health profile of a coating.

Bio-based paints are an accelerating area of interest in the industry. This area may seem niche at the moment, but there is demand from the market for product options with lower environmental impact and where the constituents of the coating are seen to be less harmful to human health. Governments are beginning to use their procurement processes to encourage more adoption of bio-based ingredients.

All of these elements seek to impact on the health of the end user. The general performance of the paint also does this, and VOC emissions have long been a performance bar for architectural coatings. But how do we gather these human-focussed elements of coatings technology into a system or structure that makes sense to an end user?

We could draw one approach from the world of design, and the concept of human-centred design. In the healthcare sector, the Center for Healthy Design promotes an evidence-based approach to improving outcomes in the built environment. This involves using research-based evidence to improve design and construction, and measuring the impact in terms of patient, staff and operational outcomes. Taking a holistic approach includes looking at the impact of materials on the occupants of healthcare facilities, and coatings have a part to play in this. Indoor air quality is an enormous factor in healthcare facilities, and some of the technologies we have looked at have a potential role to play here. 

At a consumer level, gathering various attributes of architectural coatings around the goal of creating a healthier indoor environment is the subject of a range of third-party certification programs. Many of these focus solely on VOC emissions, but the Asthma & Allergy friendly^® Certification takes a more holistic approach. It looks at the various ways that a person – particularly someone with sensitive airways, such as a person with asthma or allergies – could be exposed to elements in a coating that could be a trigger of asthma or allergies, or could reduce indoor air quality. This includes VOC emissions of course, and because the focus here is on the most sensitive individuals, emissions criteria are lower than most certifications, and measured at earlier time points. As we discussed earlier, building occupants can also be sensitive to particular constituents in a coating, such as MIT or CMIT, and so a full constituent review is carried out to ensure that constituents that are associated with health hazards are either not present or present at extremely low levels. And the third element is the performance of the coating – it must reach certain standards of scrubbability, adhesion, dry-time, etc. – to ensure a user is not exposed through touch to the constituents of the coating. 

The certification gives coatings’ manufacturers the opportunity to convey that broad bundle of benefits contributing to a healthier indoor environment to a consumer, in a holistic way. In the same way, taking an evidence-based design approach in a healthcare facility can bring together benefits from coatings and other building materials, with systems to protect and nurture the wellbeing of patients and staff, leading to better outcomes for all. Connecting to wider themes of sustainability and a human-centred approach, as well as situating the benefits of a high-quality coating within a broader eco-system of other products and impacts, is the way forward in communicating the benefits of coating technology.