An Analysis on the Effectiveness of Nitrogen Oxide Reduction from Applying Titanium Dioxide on Urban Roads Using a Statistical Method

The purpose of this study was to analyze the effect of titanium dioxide (TiO2) on reducing nitrogen oxide (NOx) concentrations using the statistical method of the Anderson-Darling test. To compare and analyze this effect, a spray-type form of TiO2 was applied to the asphalt pavement surface on urban roads. Data acquisition for NOx concentration was collected from a test section with TiO2 applied and a reference section without TiO2 applied. The probabilities of occurrence of the NOx concentration in the test and reference section were estimated and compared using the Anderson-Darling test. In sum, most of the NOx concentrations were probabilistically lower in the test section. The average probability of the NOx concentration in the test section in the ‘low’ range was 46.2% higher than in the reference section. In the ‘high’ and ‘moderate’ ranges, the average probability of the NOx concentration compared to that of the reference section was lower by 28.1% and 18.8%, respectively. These results revealed that the photochemical reaction from the TiO2 material applied on asphalt pavement was effective in reducing NOx.