Photocatalytic abatement results from a model street canyon

During the European Life+ project PhotoPAQ (Demonstration of Photocatalytic remediation Processes on Air Quality), photocatalytic remediation of nitrogen oxides (NOx), ozone (O3), volatile organic compounds (VOCs), and airborne particles on photocatalytic cementitious coating materials was studied in an artificial street canyon setup by comparing with a colocated nonactive reference canyon of the same dimension (5 × 5 × 53 m). Although the photocatalytic material showed reasonably high activity in laboratory studies, no significant reduction of NOx, O3, and VOCs and no impact on particle mass, size distribution, and chemical composition were observed in the field campaign. When comparing nighttime and daytime correlation plots of the two canyons, an average upper limit NOx remediation of ≤2% was derived. This result is consistent only with three recent field studies on photocatalytic NOx remediation in the urban atmosphere, whereas much higher reductions were obtained in most other field investigations. Reasons for the controversial results are discussed, and a more consistent picture of the quantitative remediation is obtained after extrapolation of the results from the various field campaigns to realistic main urban street canyon conditions.

Construction of a photocatalytic de-polluting field site in the Leopold II tunnel in Brussels

Within the framework of the European Life+-funded project PhotoPAQ (Demonstration of Photocatalytic remediation Processes on Air Quality), which was aimed at demonstrating the effectiveness of photocatalytic coating materials on a realistic scale, a photocatalytic de-polluting field site was set up in the Leopold II tunnel in Brussels, Belgium. For that purpose, photocatalytic cementitious materials were applied on the side walls and ceiling of selected test sections inside a one-way tunnel tube. This article presents the configuration of the test sections used and the preparation and implementation of the measuring campaigns inside the Leopold II tunnel. While emphasizing on how to implement measuring campaigns under such conditions, difficulties encountered during these extensive field campaigns are presented and discussed. This included the severe de-activation observed for the investigated material under the polluted tunnel conditions, which was revealed by additional laboratory experiments on photocatalytic samples that were exposed to tunnel air. Finally, recommendations for future applications of photocatalytic building materials inside tunnels are given.

Cense: a tool to assess combined exposure to environmental health stressors in urban areas

This paper describes the structure of the Combined Environmental Stressors' Exposure (CENSE) tool. Individuals are exposed to several environmental stressors simultaneously. Combined exposure represents a more serious hazard to public health. Consequently, there is a need to address co-exposure in a holistic way. Rather than viewing chemical and physical health stressors separately for decision making and environmental sustainability considerations, the possibility of an easy-to-comprehend co-exposure assessment is herein considered. Towards this aim, the CENSE tool is developed in the programming environment of Delphi. The graphical user's interface facilitates its tractable application. Studying different scenarios is easy since the execution time required is negligible. The tool incorporates co-exposure indicators and takes into account the potential dose of each chemical stressor by considering the physical activities of each citizen in an urban (micro)environment. The capabilities of the CENSE tool are demonstrated through its application for the case of Thessaloniki, Greece. The test case highlights usability and validation insights and incorporates health stressors and local characteristics of the area considered into a well identified user/decision maker interface. The main conclusion of the work reported is that a decision maker can trust CENSE for urban planning and environmental sustainability considerations, since it supports a holistic assessment of the combined potential damage attributed to multiple health stressors. CENSE abandons the traditional approach of viewing chemical and physical stressors separately, which represents the most commonly adopted strategy in real life decision support cases.