·Beijing released the latest round of PM2.5 source analysis mainly from motor vehicles

Beijing released the latest round of PM2.5 source analysis, local emissions accounted for 2/3, of which coal consumption accounted for 3%

Where does Beijing PM2.5 come from? Yesterday, Beijing released the latest round of PM2.5 source analysis. Research shows that local emissions account for two-thirds of the main sources of PM2.5 in Beijing, and regional transmission accounts for one-third. As the pollution level increases, the regional transmission contribution increases, and the heavy pollution day area transmission accounts for 55%-75%. Among the current local atmospheric PM2.5 sources in Beijing, motor vehicles and other mobile sources account for the largest proportion, reaching 45%.

The main source of mobile sources comes from diesel vehicles in Beijing.

What is source analysis, that is, establishing a qualitative or quantitative relationship between pollution sources and ambient air quality to determine the main targets and priorities of air pollution control is the basis of scientific policy. In other words, with this source analysis, Beijing can control where air pollution can be used to improve accuracy.

The PM2.5 source is divided into two parts, local and regional transmission. According to the study, Beijing currently accounts for 2/3 of PM2.5 local emissions, 45% of local emissions, and 1/3 of regional transmission.

The main conclusions of this study indicate that local emissions account for two-thirds of the main sources of PM2.5 in Beijing. At this stage, local sources of emissions, mobile sources, dust sources, industrial sources, living sources and coal sources are respectively 45%, 16%, 12%, 12% and 3%, accounting for 12% of other agricultural and natural sources; diesel vehicles driving in Beijing from mobile sources contributed the most, building construction and road dust in the dust source, industrial source The contribution of the volatile organic compounds industry in China's petrochemical industry, automobile industry and printing is more prominent, and the use of domestic solvents in living sources accounts for about 40%.

Heavy pollution day area transmission maximum contribution of 75%

The source analysis shows that the regional transmission accounts for 26%-42%, about one-third, and with the increase of pollution level, the regional transmission contribution shows a significant upward trend. The moderate pollution day (PM2.5 daily average concentration is Regional transmission between 115-150 μg/m3 accounts for 34%-50%, and heavy pollution day (PM2.5 daily average concentration >150 μg/m3) regional transmission accounts for 55%-75%.

According to reports, in 2017, the Beijing Municipal Environmental Protection Bureau organized the Beijing Environmental Protection Monitoring Center, Tsinghua University, the Institute of Atmospheric Physics of the Chinese Academy of Sciences and Peking University and other related units to combine scientific research projects with daily monitoring work to carry out “Beijing 2017 atmospheric PM2”. .5 Refined Source Analysis" research and recommendations for the next step in managing the atmosphere.

In 2014, Beijing released the PM2.5 source analysis for the first time. The results show that regional transmission contribution accounts for 28% -36%, and local pollution emissions contribute 64% -72%. Among the local pollution contributions, motor vehicles, coal, industrial production and dust were the main sources, accounting for 31.1%, 22.4%, 18.1% and 14.3% respectively.

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Why are mobile sources such as motor vehicles still the biggest?

The decline is lower than the overall decline of air pollutants in the city

In 2014, Beijing released the PM2.5 source analysis for the first time. Among local sources, motor vehicles contributed the most. In the latest analysis of this round, local source mobile sources accounted for 45%, which is 1.4 times of the previous round of analysis results (31.1% of motor vehicles).

Mobile sources, including diesel vehicles, gasoline vehicles, Beijing and transit diesel vehicles, non-road machinery, aviation, trains, etc. That is to say, at present, the proportion of mobile sources such as motor vehicles in Beijing's local sources is still the largest.

Specifically, among mobile sources, diesel vehicles accounted for 32%, gasoline vehicles 29%, Beijing and transit diesel vehicles 18%, non-road machinery and other 14%, aviation and trains accounted for 7%.

Why are mobile sources such as motor vehicles still the biggest ones after several years of governance? Liu Baoxian, deputy director of the Beijing Environmental Monitoring Center, said that in absolute terms, the emissions of mobile pollution sources have dropped significantly, but this decline is lower than the overall decline of air pollutants in the city, so its proportion has increased.

What are the characteristics of the new PM2.5 source resolution?

Local sources of coal-fired sources account for 3%, basically withdrawing from major sources of contribution

Liu Baoxian, deputy director of the Beijing Environmental Monitoring Center, introduced that the new round of source analysis has significant features. The contribution of local sources of emissions has changed significantly. First, the contribution of each major source to the absolute concentration of PM2.5 decreased significantly, and the decline in coal source was the most significant. Among the local sources, coal-fired sources accounted for 3% of this time, basically withdrawing from the ranks of Beijing's atmospheric PM2.5 main contribution sources. Secondly, the proportion of PM2.5 main sources is “two liters, two drops and one highlight”, the contribution rate of mobile sources and dust sources increases, the contribution rate of coal and industrial sources decreases, and the contribution rate of living sources is further highlighted.

Secondly, the local source of mobile emissions is the largest, accounting for a significant increase. Mobile sources are the largest source of local atmospheric PM2.5 at different times and in space throughout the year. Sources vary by region and time period. From different areas, the dust characteristics of coal burning in the southern boundary, urban motor vehicles and traffic sites are the most significant. From different time periods, mobile sources are the largest source, while sulfate is mainly affected by regional coal-fired transmission.

In addition, regional transmission contributions have increased. From the annual average, the regional transmission contribution rate to PM2.5 is 34% ± 8%, which is slightly higher than the previous round of source analysis results (32% ± 4%). From the contribution of heavy pollution day, the regional transmission contribution rate of heavy pollution day is 55%-75%, which is significantly higher than that of the previous round of source analysis. There is a transmission channel for regional pollution transmission, in which the southern part (especially along the Taihang Mountain line) and the eastern transmission channel contribute more.

How to control air pollution in the next step?

Experts recommend strengthening diesel vehicles, dust and life sources

According to the latest source analysis results, experts suggest that according to the "two liters, two drops and one highlighting" feature, the next step is to strengthen the governance of mobile sources (especially diesel vehicles), dust and living sources; secondly, continue to deepen regional defense Joint control work, focus on key time slots, key transmission channels, optimize industrial layout, and strengthen emergency linkage during heavy pollution; in addition, continue to strengthen scientific and technological support, enhance scientific and technological pollution control, and accurately control pollution.

Why is the pollution in Beijing recently frequent?

Unfavorable meteorological conditions and increased emissions due to peak production

Since March, there have been many air pollution processes in the Beijing area. Many citizens are worried that the air quality in Beijing this year will be significantly worse than last year. In this regard, Wang Shuxiao, a professor at the Environmental College of Tsinghua University, said that the air quality in November and December last year was really good compared to March to May this year. The reason for the recent increase in pollution is that the Beijing-Tianjin-Hebei region and surrounding areas have started peak-peak production since last winter. After March 15 this year, the peak-peak production measures have ended, and the level of industrial air pollutants in the entire region has increased.

In addition, the weather conditions from March to May this year are not very favorable, and are affected by sand and dust. At the end of this week's pollution process, Beijing was at a low-pressure convergence center, causing pollutants from surrounding areas to be transmitted to Beijing. In addition, the local air humidity in Beijing is large, which accelerates the secondary generation of particulate matter. This shows that in the future, it is necessary to strengthen the governance of local pollution, and also coordinate the atmospheric management of the entire regional transmission channel city.