Photocatalytically active building materials can contribute to better air quality by mineralizing the hazardous nitrogen oxides to nitrate. Evaluation of these materials is very important for optimization and implementation at target sites. However, the currently widely used ISO 22917-1:2016 test is unsuitable to estimate the effect on real scenarios since it employs too high concentrations and only evaluates the NO oxidation potential, completely ignoring the more relevant NO2. Herein, we present a methodology to better simulate the real-world performance of these materials based on its effect on the ternary mixture NO/NO2/O3 under environmentally relevant concentrations, which can also be simulated by means of kinetic analysis of experimentally less complex single component measurements. From this, a new figure of merit - the trend value - is derived to rate the materials' performance.
