Nanotechnologies include manufacturing techniques and processes in the microscopic world: at the scale of a nanometre, i.e. one millionth of a millimetre, 50,000 times thinner than a hair. This scale provides a wide range of innovations in many lines of business: building, energy, IT, chemicals, medicine, food processing, agriculture. There are already a large number of applications in several everyday products: ready-made meals, hygiene and cosmetic products (toothpaste, sunscreen), textiles, drug products. Even though the actual extent of this potential is still to be assessed, one unknown factor remains: possible risks to health, which urge us to apply a precautionary principle.
Titanium or silicon dioxide, zinc oxide, silver or copper nanoparticles, carbon nanotubes: nanometric compounds are all around us, in their natural state, but are also increasingly man-made. The field of nanotechnologies spread in the 2000s because of the new properties that those microscopic materials provide to products which include some of these materials: increased strength, greater flexibility or elasticity, extreme durability, improved conductivity, solubility, fire resistance, etc.
Outlook for the building industry: buildings with increased strength and a positive impact on human health
In the building industry, nanotechnologies offer new opportunities and play a part in the design of many building materials: air-cleaning paints, self-cleaning windows, self-cleaning concrete, anti-ageing stained wood, air-cleaning and antibacterial floor covering, antibacterial switches, etc.
Adding nanoparticles to concrete makes it possible to increase the strength of building structures and lighten them, while providing a flexibility that is greater than that of steel and a very high stress and compression strength. This is an opportunity to increase the durability of buildings and reduce maintenance requirements.
The air-cleaning and antibacterial properties of some nanoparticles help contemplate buildings with a positive impact on human health. For instance, using a metal such as silver can fight nosocomial infections and bacteria in healthcare facilities. Used to manufacture switches, floor covering or used in aeraulic circuits, it helps make the building sounder while reducing maintenance requirements.
Scientific uncertainties: what is the impact on health and the environment?
Although prospects are good, there are still many uncertainties regarding the risks associated with nanoparticles to human health and the environment. It is difficult to assess their overall toxicity, which depends on a number of criteria such as their physico-chemical structure, their implementation and life cycle. According to Emeric Fréjafon, in charge of activities linked to assessing the hazards and risks in the field of nanotechnologies at Ineris, the French National Institute for Industrial Environment and Risks, a concrete that contains nanoparticles may, for example, be considered as non toxic when implemented but hazardous when the building is pulled down.
In the face of these uncertainties, the precautionary principle prevails. From 2010, ANSES, the French Agency for Food, Environmental and Occupational Health & Safety, has encouraged adoption of some precautions when using those particles. In the building industry, techniques that keep dust to a minimum should be preferred, or personal protective equipment (PPE) adapted to the task to carry out (FFP3 filtering face masks, type 5 overalls, nitrile, butyl or vinyl gloves, goggles with side shields) should be used to limit exposure risks when handling materials likely to contain nanoparticles. Simultaneously, EpiNano, the French program for epidemiological surveillance of workers potentially exposed to engineered nanomaterials was launched in 2014 in conjunction with Santé Publique France to monitor and detect any potential effects four categories of engineered nanomaterials (carbon nanotubes, titanium dioxide, silicon dioxide and carbon black) may have on human health.
From a legislative perspective, since 1 January 2013 companies and laboratories in France must declare quantities and uses of the nanoparticles they produce, distribute or import on the French territory every year on the R-nano website. The purposes are to learn to know these substances and their uses better, be able to trace the uses, improve knowledge of the market, and collect information on the toxicological and ecotoxicological properties of nanoparticles.
Studies and research projects
In the building industry, there are an increasing number of studies and research projects whose twofold purpose is to explore the potential of nanotechnologies and nano-objects and increase knowledge of the health and environmental impact associated with their manufacturing and their use.
The EnDurCrete scheme (2018-2021) run in the context of the Horizon 2020 EU Research and Innovation programme aims to design innovative, “green” and sustainable concrete that includes industrial by-products and hybrid systems involving nanotechnologies.
Other research programmes focus on the long-term effect of nanocomposite materials to be used in the building industry. This is the case of the EMANE project led by CSTB, the French Scientific and Technical Centre for Building, and LNE, the French Metrology and Test Laboratory, and funded by ADEME.
“If the building industry does indeed increase its use of nanoparticles, nanoproducts and nanotechnologies, it will be urgent to learn more about them […]”, declares OGBTP (the French General Building and Public Works Office) in its special issue on nanomaterials.