Dynamic emission characteristics and control strategies of air pollutants from motor vehicles in downtown Beijing,China

This study combined the real-time monitoring and investigation of traffic flows to comprehensively analyze the road traffic flow and vehicle structure in downtown Beijing.A dynamic emission inventory of motor vehicle air pollutants in downtown Beijing in 2021 was established,and the impact of these emissions on air quality was simulated and quantified,and different emission reduction control scenarios were proposed to evaluate their environmental improvement effects and explore measures to mitigate the impact of pollution emissions.The results show that the high traffic flow and the structure of the motor vehicle emissions in downtown Beijing are the main causes of severe motor vehicle pollution.Monitoring data shows that traffic flow in central Beijing is dominated by small passenger vehicles,while the vehicle mix is better than in other regions,with 72.0%of vehicles meeting"National V"or higher emission standards.However,to achieve higher air quality goals,further reducing vehicle emissions is necessary.Based on dynamic traffic flow,the average daily emissions of nitrogen oxides(NOX),particulate matters(PM_(2.5))and volatile organic compounds(VOC)from motor vehicles in central Beijing are 17.7 tons,0.6 tons and 14.0 tons,respectively,accounting for 23.0%of the city’s average daily motor vehicle emissions.If a zero-emission zone for motor vehicles were implemented in central Beijing,the annual average emission level of pollutants will be reduced by 10.4%to 21.0%.The designation of ultra-low emission zones for motor vehicles could be effective in improving the air quality in the center of Beijing.

Vehicle emissions of primary air pollutants from 2009 to 2019 and projection for the 14th Five-Year Plan period in Beijing, China

Over the past decade,the emission standards and fuel standards in Beijing have been upgraded twice,and the vehicle structure has been improved by accelerating the elimination of 2.95 million old vehicles.Through the formulation and implementation of these policies,the emissions of carbon monoxide(CO),volatile organic compounds(VOCs),nitrogen oxides(NO_(x)),and fine particulate matter(PM_(2.5))in 2019 were 147.9,25.3,43.4,and 0.91 kton in Beijing,respectively.The emission factor method was adopted to better understand the emissions characteristics of primary air pollutants from combustion engine vehicles and to improve pollution control.In combination with the air quality improvement goals and the status of social and economic development during the 14th Five-Year Plan period in Beijing,different vehicle pollution control scenarios were established,and emissions reductions were projected.The results show that the emissions of four air pollutants(CO,VOCs,NO_(x),and PM_(2.5))fromvehicles in Beijing decreased by an average of 68% in 2019,compared to their levels in 2009.The contribution of NOx emissions from diesel vehicles increased from 35% in 2009 to 56% in 2019,which indicated that clean and energy-saving diesel vehicle fleets should be further improved.Electric vehicle adoption could be an important measure to reduce pollutant emissions.With the further upgrading of vehicle structure and the adoption of electric vehicles,it is expected that the total emissions of the four vehicle pollutants can be reduced by 20%-41% by the end of the 14th Five-Year Plan period.

Multi-dimension apportionment of clean air “parade blue”phenomenon in Beijing

The mass concentration and major chemical components of fine particulate matter were measured before,during and after Beijing＇s massive parade commemorating 70th anniversary of the Chinese Victory in World War II on September 3,2015.Regional emission inventory,positive matrix factorization（PMF）,observations from space and backward air mass trajectories were jointly applied to identify the major pollution sources and their temporal and spatial variations.The contributions of emissions variations and the meteorological conditions related to the＂parade blue＂phenomenon in Beijing and its surrounding areas were investigated in detail.The main cause of the decreased PM（2.5）mass concentration was attributed to the absolute reduction in emissions of primary air pollutants.The chemical composition of PM（2.5）varied significantly before,during and after the parade.Fugitive dust particles were well controlled,the secondary formation of PM（2.5）was reduced along with the controlled gaseous precursors＇emissions from vehicles and industrial sources during the temporary intensified control period.During the parade period,the SO2and NO2column concentrations in Beijing and the surrounding areas decreased sharply,indicating that the coordinated reduction in primary emissions from the surrounding areas of Beijing played an important role in lowering the ambient concentration of SO2and NO2and accordingly lowered PM（2.5）and improved the regional air quality.A comparison of the temperature,humidity,and wind speed and direction during the same periods in 2014 and 2015 showed that the meteorological conditions positively influenced the achievement of＂parade blue＂.

Exploring the heavy air pollution in Beijing in the fourth quarter of 2015： assessment of environmental benefits for red alerts

In recent years, Beijing has experienced severeair pollution which has caused widespread public concern.Compared to the same period in 2014, the first threequarters of 2015 exhibited significantly improved airquality. However, the air quality sharply declined in thefourth quarter of 2015, especially in November andDecember. During that time, Beijing issued the first redalert for severe air pollution in history. In total, 2 red alerts,3 orange alerts, 3 yellow alerts, and 3 blue alerts wereissued based on the adoption of relatively temporaryemergency control measures to mitigate air pollution. Thisstudy explored the reasons for these variations in airquality and assessed the effectiveness of emergency alertsin addressing severe air pollution. A synthetic analysis ofemission variations and meteorological conditions wasperformed to better understand these extreme air pollutionepisodes in the fourth quarter of 2015. The results showedthat compared to those in the same period in 2014, thedaily average emissions of air pollutants decreased in thefourth quarter of 2015. However, the emission levels ofprimary pollutants were still relatively high, which was themain intrinsic cause of haze episodes, and unfavorablemeteorological conditions represented important externalfactors. Emergency control measures for heavy airpollution were implemented during this red alert period,decreasing the emissions of primary air pollutants byapproximately 36% and the PMa.5 concentration by 11%-21%.

Ten-year emission characteristics of atmospheric pollutants from incineration of sacrificial offerings in China

The incineration of sacrificial offerings is a significant widely practiced custom that is also a kind of neglected air pollution source in China.Our results showed that the emission factors of particulate matter,SO_(2),CO,NO_(x),and VOCs emitted from the incineration of sacrificial offerings with purification systems were reduced by 95%,19%,9%,82%,and 42%,respectively,compared with those without a purification system,revealing a significant effect of the flue gas purification system on reducing particulate matter and gaseous pollutants.The emission level of air pollutants from the incineration of sacrificial offerings remained stable before 2013 and then showed a remarkable decrease after the implementation of China′s Air Pollution Prevention Action Plan in 2013.The emissions of TSP(total suspended particulate),PM_(10),PM_(2.5),and NO_(x)in 2009 were 8222,6106,5656 and 15,878 ton,respectively,obviously higher than 3434,2551,2305 and 8579 ton in 2019.Such trend was affected by both the quantity of incineration and the installation rate of purification systems after the Emission Standard of Air Pollutants for Crematory(GB 13801-2015)issued in China.Distinct spatial distribution of atmospheric pollutants from incineration of sacrificial offerings was found with higher in the east and south of China than the west and north of China,which is proportional to the regional economy and population.The maximum ground-level concentration typically occurred at 0.12-0.2 km from the pollution source,posing potential health risks to people entering and exiting funeral and burial sites and nearby residents.