Air quality is one of the most important parameters for measuring the livability of an urban center, considering the direct effects that pollution can have on human health. This is precisely why over the last 15 years the problem of fine particles such as PM10 and PM2.5 has become a central issue for the Administrations of major European cities, which have deployed resources and designed strategies with the aim of fighting this growing emergency. From the ban on certain models of diesel engines to the expansion of shared mobility, from the now familiar 30 km/h zones to restrictions related to the management of domestic heating, right through to visionary plans for the development of urban green spaces: in the city, boilers and internal combustion engines are the primary cause of air pollution, but this is a relative value, because there are other factors related to themes differing from the urban environment, such as intensive livestock farms, air transport and industrial facilities.
Reducing the level of smog and improving air quality is therefore a complex battle, which can only be won by a combination of virtuous attitudes on the part of municipalities, citizens, and private businesses.
GreenGraffiti has been created as a sustainable alternative to classic billboard advertising, a tool that can fulfill the task of communication within the city while limiting the resources used and eliminating the production of waste. The messages are installed directly on the paving of squares and sidewalks without the need for plastic or paper supports. The material used for the installation is a sophisticated food-grade paint, easily removed with a simple jet of hot water without additives or solvents.The technique was developed with a green approach, and in combination with the Pureti® system, it becomes a diffuse smog-absorbing solution that can make a substantial contribution to cleaning air in the city.
Pureti® is a nontoxic compound, part of the European iSCAPE project. By means of a photocatalytic process, it enables the creation of a protective layer capable of oxidizing the lightweight molecules with which it comes into contact. It is a substance constructed in the form of a matrix of nanoparticles that, activated and empowered by solar energy, acquire a form of accelerated motion to protect the material on which they are placed, deactivating harmful molecules and releasing oxygen into the air.The factor that sets this system apart from other similar technologies is the mode of application, which involves the creation of a nano-mesh covering layer entirely exposed to sunlight. For each square meter of coating, it is designed to guarantee a level of performance, in terms of reducing PM10, PM2.5 and PM0.5 levels and purifying the air, comparable to that of an average-sized tree.
Each GreenGraffiti message is treated with Pureti® so that it is transformed into an active anti-pollution agent: taking Milan as a sample city and considering a 15-day campaign exposure, the average total activity performed on the urban territory over the space of 12 months reduces the presence of harmful pollutants such as NOx, SOx and VOCs to the same degree as that achieved by about 120 trees, in other words, as much as a city park.
This is a form of good practice that, although not a cure-all with respect to the complexity of the problem, nonetheless contributes effectively to the decontamination of the environment, and consequently improves the quality of life in cities.