A joint prevention and control mechanism for air pollution in the Beijing-Tianjin-Hebei region in china based on long-term and massive data mining of pollutant concentration
Graphical abstract
BJ and the 9 cities i.e. LF, TJ, BD, TS, CZ, HS, SJZ, XT, HD, the latitude of which is lower than that of BJ, are the key cities in JPCAP oriented to the two pollutants in BTH region in China. For JPCAP oriented to PM2.5 and PM10, the key JPCAP regions and corresponding pollution control grades are consistent. These results provide a scientific basis for formulating long-term, stable, and unified JPCAP strategies for the BTH region and implementation of JPCAP measures that focus on the specific problems of each region.
Introduction
The update of the urban air quality database by the World Health Organization (WHO) on 12 May 2016 revealed that more than 80% of the world's people who live in urban areas that monitor air pollution were exposed to air quality levels that exceed WHO limits. According to the monitoring data from 2011 to 2015, the five megacities (those with a population of more than 14 million) with the highest particulate matter pollution level were New Delhi, Cairo, Dhaka, Calcutta, and Mumbai. All of these cities are located in developing countries. The situation in the developed world is better, since most countries in Europe and America have already paid a heavy price to control their air pollution. However, weak environmental protection awareness and lower-level environmental initiatives in developing countries mean that, at present, many countries plagued by air pollution lack a scientific mechanism for air pollution control.
In recent years, air pollution has become an increasingly prominent problem in China. This has aroused heated discussion both at home and abroad. Air pollution in China has distinct regional characteristics. For example, the Beijing-Tianjin-Hebei (BTH) region has some of the most severe air pollution in China, and exhibits repeated outbreaks of fog and haze. Particulate-matter pollution in the 2.5- and 10-μm categories (PM2.5 and PM10, respectively) has become a major component of the pollution problem in the BTH region (Wang and Hao, 2012). Because the air pollution status in a city depends not only on itself, but also on other cities surrounding it, Joint Prevention and Control of Atmospheric Pollution (JPCAP) is an effective way to improve regional air quality. As early as May 2010, the Ministry of Environmental Protection (MEP) of the People's Republic of China, together with eight other ministries, proposed guidelines for promoting the control of multiple pollutants and regional air pollution (MEP, 2010). This was the first comprehensive policy document that aimed to improve regional and urban air quality in China. This document designated the BTH region as one of three key regions in which to implement JPCAP, and proposed to establish a unified mechanism for planning, monitoring, supervision, evaluation, and coordination of the regional JPCAP. In September 2013, a regional JPCAP mechanism was established to promote synergy of pollution management in the BTH region and to implement 10 measures determined at an executive meeting of the State Council in June 2013.
To address the air pollution problem in the BTH region, China's government has formulated a series of programs and measures. MEP and other departments jointly issued the document on detailed rule for the implementation of air pollution prevention and control action plan in the BTH region and the surrounding areas. Many heavily polluting enterprises were eliminated and the coal-fired units in Takai thermal power plants were fully shut down. Driving restrictions were implemented and a lot of vehicles that did not meet current pollutant emission standards were eliminated. Despite these efforts, the annual MEP ranking of the 10 worst cities for air quality included 7 cities in the BTH region in 2013 (MEP, 2014), 8 in 2014 (MEP, 2015), and 7 in 2015 (MEP, 2016). Thus, achieving success for JPCAP in the BTH region will be a long-term process and air pollution control will remain a severe challenge (Hao et al., 2007). Clarifying how to carry out JPCAP in the BTH region has become the top priority of environmental coordination development in the region.
The atmosphere is a very complicated system. In BTH, the PM2.5 and PM10 pollution status were affected by several key factors, such as local emissions of both primary particles and gaseous precursors, regional transport of particles and gaseous precursors, topography and meteorology. The deep research on the correlation among air pollution in the cities should be carried out and the cities should be divided into different JPCAP region according to the correlation characteristics. On this account, firstly, the division of JPCAP region cannot be simply based on administrative region division or short-term pollutant concentration data. It should be based on long-term pollutant concentration data and from the perspective of the correlation of pollutant concentration between cities. Secondly, the pollution status, the industrial status and the urban development level etc, in the regions are different. In addition, pollution control requires great financial support. There should be priority in the implementation of pollution control in the JPCAP regions to ensure the JPCAP program is targeted. Therefore, identifying the key JPCAP regions within the BTH region and the corresponding pollution control grades will be a crucial step for formulating long-term policy on JPCAP and implementing JPCAP effectively. Without grasping the core issues, the air pollution in BTH can not be fundamentally solved.
Recently, many researchers have concentrated on air pollution levels during specific periods (Wang et al., 2014) or in specific regions and some representative cities of those regions (Han et al., 2010, Huang et al., 2014, Liu et al., 2013, Wang et al., 2016). Some researchers have focused on the formation of air pollution (Feng et al., 2012, Pathak et al., 2009), its development (Peng et al., 2016), and its apportionment among sources (Hua et al., 2015, Wang et al., 2015). Others have analyzed regional spatial and temporal variations of air pollution (Chow et al., 1994, Gomiscek et al., 2004, Hu et al., 2014). These researches are mostly focused on short-term pollution status, not based on long-term and massive pollutant concentration data. Although some have studied mechanisms for regional atmospheric pollution control (RAPC) in specific cities from a micro-scale perspective (Zhang et al., 2016) and theoretical and methodological aspects of JPCAP from a macroscopic perspective (Wang et al., 2012), the division of JPCAP region was only based on economic or social analyses, or only air basin theory. Many researchers have focused on the regional air pollution control (Bergin et al., 2005, Castells and Ravetz, 2001) and the cost-effectiveness of JPCAP (Wu et al., 2015). Owing to the diverse conditions under which the pollution forms and the diverse opportunities for its spread, as well as differences in the national conditions (e.g., stage of economic development, climate) that affect the pollution, little research (e.g., Nordenstam et al., 1998) presently exists on mechanisms to optimize JPCAP, especially from the perspective of combining control at key local sources with regional joint prevention and control.
In practice, owing to a lack of institutional arrangements, clear ideas, and scientific evidence, few long-term JPCAP practices are currently being used in China and other countries around the world. Our current research started with an analysis (Wang et al., 2016) of the spatiotemporal distributions of pollutants. In the present study, we used long-term tracking data, government summaries, and data mining to obtain PM2.5 and PM10 concentration data that let us analyze the status of these pollutant categories in the BTH region and explore potential mechanisms to implement JPCAP focused on PM2.5 and PM10. In addition, because air quality index (AQI) is the primary metric of air quality and at the same pollutant concentration level, the influence of PM2.5 on air quality is greater than that of PM10 (Table 1), individual air quality index (IAQI) as standardized metric of air quality oriented to different pollutants was used in this study. Here, we used the method for calculating IAQI values from the Technical Regulation on Ambient Air Quality Index (HJ 633–2012) issued by MEP in 2012 (http://kjs.mep.gov.cn/hjbhbz/bzwb/dqhjbh/jcgfffbz/201203/W020120410332725219541.pdf).Our goals were to support the development of suitable control measures and formulate a long-term JPCAP strategy, while also advancing research on scientific and rational ways to analyze the JPCAP problem and formulate related pollution-control schemes. The present study represents, to the best of our knowledge, the first attempt to empirically define a JPCAP region and identify the distribution of pollution grades within the region. The method can also be applied to other regions of the world plagued by air pollution to support regional efforts to improve the air quality many countries plagued by air pollution lack a scientific mechanism for air pollution control.
Section snippets
Temporal sample space
Because JPCAP in the BTH region is a long-term measure, its strategy should be developed based on an analysis of the regional air quality status during a long period. In this study, we collected the concentration data for the two primary pollutants, PM2.5 and PM10, from 1 February 2013 to 31 January 2016, a total of 36 months. The data themselves contained comprehensive information about regional air pollution, such as the characteristics of the pollutants, local geographical characteristics,
Air quality status in the BTH region
Fig. 2, Fig. 3 show the seasonal air quality status in the BTH region for PM2.5 and PM10, respectively. Fig. 2 shows that the PM2.5 pollution was more severe in autumn and winter than in the other seasons, with the most severe pollution in winter and the lightest pollution in summer. For PM2.5, the pollution was most severe in the south and southwest, and was lightest in the northwest. Fig. 3 shows that the PM10 pollution was also most severe in winter and lightest in the summer. The most
Discussion
We collected 3 years of PM2.5 and PM10 data for the BTH region, from February 2013 to January 2016, and focused our research on developing a JPCAP to reduce PM2.5 and PM10. Using the IAQI values as standardized measurement for the two pollutants, we mapped the air quality status throughout the BTH region and analyzed the seasonal variation of pollutants, and the relationship between the correlation coefficients for the winter DACs for the two pollutants and the distances between cities, and
Conclusions
Based on long-term data collection for PM2.5 and PM10, we mapped the spatial and temporal characteristics of the two pollutants in the BTH region. PM2.5 and PM10 pollution was most severe in winter, with PM2.5 showing regional, large-scale, concentrated pollution and PM10 showing local, small-scale, multi-place pollution. Through the observation of Fig. 2, Fig. 3 and the data from Table 2, we found the air quality north of Beijing was obviously better than that within the regions south of
Acknowledgments
This research was supported by the National Natural Science Foundation of China (project No. 71373155), the National Social Science Foundation of China (Project No. 16BGL146), and by the Chinese Ministry of Education Project on the Key Projects of Philosophy and Social Sciences (13JZD025). The authors thank the China National Environmental Monitoring Center for providing the information used in our analysis.
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