Numerical study of the effect of traffic restriction on air quality in beijing

The Nested Air Quality Prediction Modeling System (NAQPMS), in coupling with the fifth-generation NCAR/Penn State Mesoscale Model (MM5), is employed to assess the impact of vehicle traffic restriction on air quality in Beijing within pre-Olympic environmental measures implemented from 17^th to 20^th August 2007. Predictions are compared against meteorological and air quality observed data and validation shows model good performance as a whole. Sensitivity experiments, including the baseline and traffic control scenarios, are designed to estimate the potential reduction of nitrogen dioxide (NO₂) and particulate matter (PM10) concentrations during the traffic restriction. Results indicate that the NO₂ concentration in Urban Beijing is reduced by 16%~32%, with the average of 21%, while NOx emissions are lowered within 28%; the primary PM10 concentrations is also reduced by 6%~15%, lower than the decreased percentages of NO2 concentration. The results show that the most significant reduction of air pollutants occurs in Urban Beijing where the restriction has been mainly imposed. This study demonstrates the efficiency of traffic restriction measure in air quality improvement over Beijing. © 2010, the Meteorological Society of Japan.