Air quality is one of the most important parameters for measuring the livability of an urban environment, given the direct impact that pollution can have on human health.
For this reason, over the past 15 years the spread of pollutants such as fine particulate matter or nitrogen oxides has become a central issue for the administrations of major European cities, which have invested resources and developed strategies to address this growing emergency. From restrictions on certain diesel engines to the expansion of shared mobility, from widely adopted 30 km/h zones to regulations on domestic heating systems, and even long-term urban greening plans: within cities, boilers and combustion engines remain among the primary sources of air pollution. However, this is a relative primacy, shared with factors beyond the urban context, such as intensive farming, air transport, and industrial facilities. Reducing smog levels and improving air quality is therefore a complex challenge that can only be addressed through the combined efforts of municipalities, citizens, and private companies.
GreenGraffiti was created as a sustainable alternative to traditional outdoor advertising - a communication tool designed to operate within urban spaces while limiting resource consumption and eliminating waste production. Messages are installed directly onto pavements and sidewalks without the need for plastic or paper supports; the material used is a refined, food grade paint that can be easily removed with a simple jet of hot water, without additives or solvents.
This technique, developed with a responsible approach, is further enhanced through the application of an active photocatalytic coating capable of contributing significantly to cleaner air. The treatment applied to each installation is a non-toxic compound based on photocatalytic technology. When activated by natural light, it triggers an oxidation process capable of transforming and reducing some of the main airborne pollutants.
The formulation consists of a matrix of Titanium Dioxide (anatase) nanoparticles which, once energized by sunlight, initiate a natural chemical process capable of deactivating harmful molecules upon contact with the surface, contributing to the reduction of:
• Nitrogen oxides (NOx)
• Organic component of particulate matter (PM10, PM2.5 and ultrafine fractions)
• Volatile organic compounds (VOCs)
The application creates a uniform surface network fully exposed to light, designed to maintain long-term effectiveness without altering the visual appearance of the artwork.
Each treated square meter becomes an active surface interacting with its surroundings, contributing in a measurable and continuous way to the improvement of urban air quality.
Case study: taking Milan as a sample city and assuming an average exposure of 15 days per campaign, the combined installations carried out over 12 months generate an estimated overall environmental impact comparable to that of approximately 50 medium-sized trees, equivalent to the diffuse presence of a small green area within the city.
This therefore represents a good practice which, while not a definitive solution to the complexity of the problem, makes a concrete contribution to environmental decontamination and the consequent improvement of urban quality of life.
