How much does traffic flow modification change air quality? Scenario-based study

Area of Science:

• Environmental Science
• Urban Planning
• Air Quality Management

Background:

• Urban air pollution is a major environmental and health concern.
• Wrocław, Poland, faces significant air quality challenges due to high traffic congestion.
• Nitrogen oxides (NOx) are key pollutants impacting urban environments.

Purpose of the Study:

• To analyze the impact of traffic reduction scenarios on NOx concentrations in Wrocław.
• To quantify the relationship between traffic volume changes and NOx levels.
• To evaluate the effectiveness of traffic management strategies for improving urban air quality.

Main Methods:

• Utilized a nine-year dataset (2015-2023) of traffic, meteorological, and air quality data.
• Developed and applied machine learning models including Random Forest, Stochastic Gradient Boosting, and XGBoost.
• Simulated traffic modification scenarios ranging from -40% to +40%.

Main Results:

• A consistent linear decrease in NOx concentrations was observed with traffic reduction.
• Increasing traffic led to a quadratic rise in NOx pollution levels.
• A 10% traffic reduction yielded approximately 2.47μgm⁻³ NOx decrease, while a 10% increase resulted in an 8.0μgm⁻³ rise.

Conclusions:

• Local traffic restrictions may be insufficient for city-wide air quality improvement.
• Comprehensive strategies focused on overall traffic reduction are crucial for substantial air quality gains.
• Data-driven modeling provides valuable insights for urban air pollution mitigation.