Potential ambient NO2 abatement by applying photocatalytic materials in a Spanish city and analysis of short-term effect on human mortality

Abstract

Road traffic is the main contributor to NO2 emissions in many European cities, causing that the current limit values for the protection of human health are exceeded. The use of photocatalytic compounds that incorporate titanium dioxide (TiO2) is frequently proposed as abatement technology but its depolluting effectiveness on a real scale is still being investigated. In this work, the potential removal capacity of NO2 that selected TiO2-based materials would have if they were implemented in a street in the municipality of Alcobendas (Community of Madrid, Spain) has been evaluated. The number of avoided NO2-related deaths over the locality across the period 2001–2019 have been inferred. Moreover, the saving associated with the estimated removal of ambient NO2 due to the use of photocatalytic materials and costs generated by their acquisition and implementation in the selected urban environment were briefly studied. Attributable mortality due to NO2 concentrations for Alcobendas has been estimated in 289 deaths, being 9241 the total deaths due to natural cause. This presents a monthly variation associated with the evolution of both mortality due to natural causes and the average concentrations of NO2. The reduction in mortality via the hypothetical implantation of photocatalytic materials throughout the municipality, assuming ideal conditions for their optimal performance, would be a maximum of 3%. In addition, a saving of €5708 yr− 1 km− 2 related to NOx damage costs of transport was obtained. A total cost of k€4750.5 km− 2 was associated to the purchase of photocatalytic materials and their application to all surfaces in that area. This technology has a big elimination potential in controlled conditions but a low reduction of ambient NO2 is provided when implemented in real outdoor urban scenarios. Its use can be recommended incorporated into engineering designs and applications, complementing other abatement measures, to reduce NO2 mortality in urban areas