Status of near-road air quality monitoring stations and data application

In order to evaluate the impact of traffic emissions on urban air quality, an increasing number of cities have established near-road air quality monitoring stations (hereafter referred to as roadside stations). This study reviews the system of roadside stations, the data application, and the evolution of air pollutant concentrations in the traffic environment in typical cities, and proposes optimization suggestions roadside stations in the future. The results show a steady increase in publications on roadside stations over the years, with the annual average number of publications after 2020 being approximately 10 times the annual mean during 1994-2001. The literature mainly focused on 'air pollution', 'particulate matter', 'emission', etc., highlighting the impact of traffic emissions on urban air quality and human health. The purpose and principles of setting up roadside stations vary from country to country, but they are mainly used to assess the impact of vehicle emissions on air quality and to protect human health in the vicinity of roads. Over the past decade, near-road NO2 concentrations in typical cities have decreased by 30%-50%, although they remain higher than those observed in the urban atmosphere. The comprehensive analysis based on long-term data from roadside stations can provide insight into the effectiveness of vehicle emission control measures, and serve as a scientific basis for the formulation of future public health protection policies.