Polar Grid-based Nonparametric Trajectory Analysis for Improved Near-Source Air Pollutant Monitoring Applications

Area of Science:

• Environmental Science
• Atmospheric Chemistry
• Air Quality Monitoring

Background:

• Nonparametric Trajectory Analysis (NTA) traditionally uses regular grids, limiting spatial detail near pollution sources.
• Previous NTA methods struggled to capture localized pollutant impacts effectively.

Purpose of the Study:

• To introduce and evaluate a modified NTA using a polar grid for enhanced spatial resolution near monitoring sites.
• To compare the performance of Polar NTA against the traditional gridded NTA.

Main Methods:

• Implemented a polar grid-based NTA to refine spatial variability analysis.
• Collected one year of continuous air pollutant data (NOx, BC, PM2.5) from a near-road monitoring site.
• Compared Polar NTA results with traditional NTA, analyzing wind data and pollutant concentrations.

Main Results:

• Polar NTA revealed higher pollutant contributions from areas closest to the roadway, with significant average concentrations for BC and NOx.
• Estimated maximum contributions increased by 22% for BC and 39% for NOx using Polar NTA.
• Analysis of background-subtracted PM2.5 indicated contributions from both roadways and nearby point sources.

Conclusions:

• Polar NTA significantly enhances the resolution and accuracy of source impact assessments in near-source monitoring.
• The method effectively differentiates contributions from various local pollution sources, improving understanding of air quality.
• Polar NTA is a valuable tool for detailed local air quality studies, especially in complex urban environments.