Field study of NOx degradation by a mineral-based air purifying paint

This paper studies the performance of a mineral-based transparent air purifying paint. The air pollutants removal efficiency of this photocatalytic paint was first determined following the ISO 22197-1 procedure under laboratory conditions. Subsequently, its air pollutants removal efficiency under realistic conditions was determined by outdoor monitoring with a duration of 20 months, applying a new monitoring protocol. The weather conditions, including temperature, wind flow, humidity, precipitation, and NOx concentration were continuously monitored. The efficiency of the photocatalytic paint was analyzed. The influence of the environmental parameters on the air pollutant removal efficiency as well as long term performance was discussed. The results show the excellent air purifying efficiency of this new paint, nevertheless the environmental parameters show dramatic effects on its long term performance. Furthermore, this study also confirmed the robustness of the proposed air purification performance monitoring protocol.