◎Our reporter Li He

　　[witnesses say]

　　In the main building of the Beijing Ecological Environment Monitoring Center, there is a special calendar chart showing the concentration of fine particulate matter (PM2.5) every day in Beijing since 2013.

"The darker and redder the color, the worse the air quality; the lighter and greener the color, the better the air quality." said Liu Baoxian, a representative of the 20th National Congress of the Communist Party of China and director of the Beijing Ecological Environment Monitoring Center. In the past decade, Beijing's air quality has improved significantly.

"From 2013, when I looked forward to the blue sky, now the blue sky has gradually become the norm, and the blue sky and white clouds have become the background of happiness for Beijing citizens."

　　In 2021, Beijing's air pollution control will achieve a milestone breakthrough, and the air quality will fully meet the standard for the first time.

The average annual concentration of PM2.5 decreased by 63.1% compared with 2013, with an average annual decrease of 7.9%, far exceeding the decline rate of cities in developed countries over the same period.

In 2021, the number of days with good air quality in Beijing will be 288, an increase of 112 days from 2013, and an increase of nearly 4 months.

　　In 2013, my country implemented the new "Ambient Air Quality Standards", and Beijing became one of the first cities in China to officially release PM2.5 monitoring data.

PM2.5 source analysis is an important support for the scientific and precise pollution control of the atmosphere.

Liu Baoxian said that Beijing has carried out three PM2.5 source analysis, and through precise measures, the air quality has been improved step by step.

　　From 2012 to 2013, Beijing carried out PM2.5 source analysis for the first time. The analysis results showed that regional transmission accounted for about 1/3; among local emission sources, mobile sources accounted for 31.1%, coal-fired sources accounted for 22.4%, and dust sources and industrial source.

Therefore, the "Beijing 2013-2017 Clean Air Action Plan" focuses on the governance of the four local sources, and at the same time takes part in the regional joint prevention and control combined with the characteristics of regional transmission.

　　From 2017 to 2018, Beijing carried out the second PM2.5 source analysis, and found that the proportion of regional transmission has increased; among local sources, mobile sources still account for the largest proportion, reaching 45%, and dust sources have risen to the second place. accounted for 16%, and coal-fired sources dropped to 3%.

　　"The source analysis results show that after treatment, various air pollution sources in Beijing have shown a significant downward trend, indicating that the clean air action plan is scientific and the measures are accurate." Liu Baoxian said that according to changes in air pollution sources, especially for the local Beijing Mobile sources, dust sources, industrial sources and living sources, Beijing has formulated the "Beijing Three-Year Action Plan to Win the Blue Sky Defense War" for 2018-2020.

　　From 2020 to 2021, Beijing conducted the third PM2.5 source analysis.

The latest source analysis found that regional transmission has increased, especially in heavily polluted weather, and regional transmission accounts for more than 60%.

Among local emission sources, mobile sources are still the most important source of air pollution in Beijing, and living sources have gradually jumped to the second place.

"This shows that the improvement of Beijing's air quality is not only due to the improvement of air quality in the entire region, but also to scientific and accurate action plans, while pollution control is increasingly dependent on regional joint prevention and control." Liu Baoxian said.

　　In September 2012, Beijing announced the distribution map of PM2.5 monitoring sites, with a total of 35 sites.

Three years later, Beijing faces more refined management needs.

"With the continuous deepening of air pollution control, large fixed emission sources such as factories have basically met the requirements, but mobile sources, dust sources, and living sources are still wide-ranging and highly mobile." Liu Baoxian said, this requires the The monitoring methods are further matched to the corresponding pollution source areas to improve the spatial resolution of monitoring.

The original monitoring can only go to the district level, and now it is necessary to extend the monitoring network to more than 300 streets, towns and other management tips.

　　Therefore, Liu Baoxian led the team to use the Internet of Things to associate all monitoring equipment for easy management and application.

At the same time, artificial intelligence is used to extend traditional algorithms to various sites, establish a cloud quality control system, and improve data quality.

"For example, we have established a local high-value identification algorithm. After having massive data, we can eliminate the influence of transmission and weather to characterize the characteristics of local pollution, so as to carry out precise control." Liu Baoxian said that this monitoring method has been spread to the whole country.

　　During this year's Beijing Winter Olympics, in order to serve the Winter Olympics well, Liu Baoxian led a team to build a set of refined air quality forecasting and forecasting systems, so that forecasts can be refined from days to hours, and forecasts for the entire region can be refined to kilometers level to support Beijing's daily air quality standards.

　　"Although Beijing's air quality has improved significantly, the prevention and control of air pollution is characterized by long-term, complex and arduous nature. To achieve long-term stability and compliance, Beijing still needs to persevere and work hard for a long time." Liu Baoxian said that in the joint efforts of everyone With hard work, "we have the confidence to harvest more and more blue sky".

(Source: Science and Technology Daily)