Summer was once a season for maximizing time spent outdoors, but the increasing frequency and severity of wildfires have made breathing outdoor air hazardous in many regions. The United Nations estimates that the number of wildfires worldwide will increase 50% by 2100 and warns that governments remain unprepared. Wildfire emissions contain small particles (PM2.5), ozone, carbon monoxide, nitrous oxide, and other pollutants that pose direct human health risks, such as asthma attacks and other respiratory ailments.
Given the guidance to limit one’s time outdoors during such events, buildings are a critical shield against pollution’s adverse effects. Ensuring a well-sealed architectural envelope and using effective filters (like MERV 13 models) in HVAC equipment can help reduce wildfire smoke penetration in buildings. In addition to these strategies, advances in material technologies demonstrate how exterior and interior surfaces can play essential roles in mitigating air pollution.
For example, researchers at Germany’s Rhine-Westphalian Technical University of Applied Sciences Aachen have developed a textile-based façade system that improves air quality. Created in partnership with German real estate developer ECE, the air-purifying product is made of a fine mesh-polymer fabric derived from recycled PET bottles. The active ingredient is a photocatalytic coating that causes nitrogen oxides to bind to the surface in the presence of sunlight. The pollutants are then converted via oxidation into non-toxic salts, which wash off the self-cleaning surface during rain events. A test application of the anti-smog textile, which demonstrated a 55% reduction in airborne nitrogen oxides, was installed on an ECE office building in Hamburg in 2020.
3M offers another pollution-fighting surface in the form of a roofing application. The Minnesota company’s Smog-reducing Granules, created by its Industrial Mineral Products Division in 2018, are photocatalytic particles used to coat roofing products like residential asphalt shingles. A test by the Lawrence Berkeley National Laboratory in California revealed that 3M shingles composed of 5% Smog-reducing Granules and 95% conventional granules measurably reduced nitrogen oxide. According to 3M, one ton of these granules can mitigate the equivalent of a year’s worth of smog generated by one vehicle traversing 3,000 miles.
Other technologies absorb atmospheric carbon. Seville, Spain-based Graphenstone manufactures air-purifying paints that absorb carbon as they cure. As the lime-based paint dries, it reacts with carbon dioxide and forms calcium carbonate. While this conversion process is most pronounced during the initial curing, it continues throughout the life of the material. A test conducted on a paint application at a hospital in Ecuador revealed impressive results. “Before painting, the CO2 value was three and a half times higher than the value reported after the paint application, going from 16,830 to 4,809 parts per million,” the manufacturer explains. This significant reduction allowed the air quality to meet the pollution limit—5,000 parts per million—established by the Occupational Safety and Health Administration.
Wallpaper is another product for the air-cleaning arsenal. Italy-based manufacturer Caos Creativo offers the Ecopur Air-Wall, a surface treatment that removes a variety of airborne pollutants, including smog particles as well as bacteria and other pathogens. The wallpaper utilizes ionizing resin that functions with or without ambient light, passively purifying the air and removing undesirable odors. The manufacturer explains that air should ideally have a concentration of 1,000 to 3,000 negative ions per cubic centimeter, the equivalent air quality of most exurban areas, and claims that the Ecopur Air-Wall results in a range of 2,000 to 4,000, comparable to “mountain and forest air,” according to its website.
Living systems can also contribute to the pollution-mitigating cause. London-based ecoLogicStudio has developed a variety of bio-based installations that utilize living organisms such as microalgae to improve environmental quality. The firm’s recent Habitat One project in Seoul, South Korea incorporates 40 algae photobioreactors, a biomass-harvesting photosynthetic reactor wall, and a multistory carbon-capturing tree sculpture. As a holistic system, Habitat One demonstrates how air purification, carbon sequestration, and biomass generation may be employed as interrelated strategies. “Imagining a carbon-neutral city implies the complete redefinition of all our production, construction and waste recycling processes,” ecoLogicStudio co-founder Claudia Pasquero told Dezeen.
Considering the increased occurrences of wildfires and other forms of atmospheric air pollution, buildings will serve as vital refuges. “Buildings are a critical element for climate resiliency,” claimed John Mandyck, CEO of New York–based nonprofit Urban Green Council, in a Bloomberg interview. Airtightness and mechanical filtration are proven methods for ensuring buildings’ effectiveness in this role, but material-based solutions also represent compelling enhancements for the air-purifying toolkit. Because most material solutions are passive in nature, they do not increase operational energy use and continue to function in the event of power outages. Given our future meteorological outlook, architects should consider combining mechanical and surface-based strategies to improve overall air quality.
The views and conclusions from this author are not necessarily those of ARCHITECT magazine or of The American Institute of Architects.