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Fine particulate matter (PM 2.5 ) pollution has been a major issue in many countries. Considerable studies have demonstrated that PM 2.5 pollution is a regional issue, but little research has been done to investigate the regional extent of PM 2.5 pollution or to define areas in which PM 2.5 pollutants interact. To allow for a better understanding of the regional nature and spatial patterns of PM 2.5 pollution, This study proposes a novel framework for delineating regional boundaries of PM 2.5 pollution. The framework consists of four steps, including cross-correlation analysis, time-series clustering, generation of Voronoi polygons, and polygon smoothing using polynomial approximation with exponential kernel method. Using the framework, the regional PM 2.5 boundaries for China are produced and the boundaries define areas where the monthly PM 2.5 time series of any two cities show, on average, more than 50% similarity with each other. These areas demonstrate straightforwardly that PM 2.5 pollution is not limited to a single city or a single province. We also found that the PM 2.5 areas in China tend to be larger in cold months, but more fragmented in warm months, suggesting that, in cold months, the interactions between PM 2.5 concentrations in adjacent cities are stronger than in warmer months. The proposed framework provides a tool to delineate PM 2.5 boundaries and identify areas where PM 2.5 pollutants interact. It can help define air pollution management zones and assess impacts related to PM 2.5 pollution. It can also be used in analyses of other air pollutants., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

The Beijing-Tianjin-Hebei area faces a severe fine particulate matter (PM2.5) problem. To date, considerable progress has been made toward understanding the PM2.5 problem, including spatial-temporal characterization, driving factors, and health effects. However, little research has been done on the dynamic interactions and relationships between PM2.5 concentrations in different cities in this area. To address the research gap, this study discovered a phenomenon of time-lagged intercity correlations of PM2.5 time series and proposed a visualization framework based on this phenomenon to visualize the interaction in PM2.5 concentrations between cities. The visualizations produced using the framework show that there are significant time-lagged correlations between the PM2.5 time series in different cities in this area. The visualizations also show that the correlations are more significant in colder months and between cities that are closer, and that there are seasonal changes in the temporal order of the correlated PM2.5 time series. Further analysis suggests that the time-lagged intercity correlations of PM2.5 time series are most likely due to synoptic meteorological variations. We argue that the visualizations demonstrate the interactions of air pollution between cities in the Beijing-Tianjin-Hebei area and the significant effect of synoptic meteorological conditions on PM2.5 pollution. The visualization framework could help determine the pathway of regional transportation of air pollution and may also be useful in delineating the area of interaction of PM2.5 pollution for impact analysis.

Exposure to fine particulate matter (PM 2.5 ) has been associated with mortality, but the extent of the adverse impacts differs across various regions. A quantitative estimation of health effects attributed to PM 2.5 in China is urgently required, particularly because it has the largest population and high air pollution levels. Based on the remote sensing-derived PM 2.5 and grid population data, we estimated the acute health effects of PM 2.5 in China using an exposure-response function. The results suggest the following: (1) The proportion of the population exposed to high PM 2.5 concentrations (>35 μg/m 3 ) increased consistently from 2000 to 2011, and the population exposed to concentrations above the threshold defined by World Health Organization (WHO) (>10 μg/m 3 ) rose from 1,191,191,943 to 1,290,562,965. (2) The number of deaths associated with PM 2.5 exposure increased steadily from 107,608 in 2000 to 173,560 in 2010, with larger numbers in the eastern region. (3) PM 2.5 health effects decreased in three pollution control scenarios estimated for 2017, i.e., the Air Pollution Prevention and Control Action Plan (APPCAP) scenario, the APPCAP under WHO IT-1 scenario (35 μg/m 3 ), and the APPCAP under WHO IT-3 scenario (15 μg/m 3 ), which indicates that pollution control can effectively reduce PM 2.5 effects on mortality.

Particulate matter data obtained from the national air quality monitoring network in China has become an essential and critical data source for many current and forthcoming studies as well as the formulation and implementation of air pollution regulatory policies on particulate matter (PM2.5 and PM10). However, the quality control of this data is dubitable and can affect many future studies and policies. This study identifies and elucidates two significant quality control issues with the data. They are PM2.5 levels exceeding concurrent co-located PM10 levels and the registration of same concentrations for consecutive hours at some stations. Future studies utilizing particulate matter data need to acknowledge and address these issues to ensure accurate and reliable results., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Transboundary particulate matter (PM) pollution in Northeast Asia has raised tremendous concerns in China, South Korea, and Japan, leading to a proliferation of publications in recent years. This article summarizes the existing knowledge on the source-receptor relationship (SRR) of transboundary PM pollution between China, South Korea, and Japan with a focus on approaches, current understanding, and limitations. We found that eastern-, northern- and northeastern China are the most contributing source areas within China to PM pollution in both South Korea and Japan, but it remains debatable whether China contributes more PM pollution to South Korea or Japan than those countries themselves. Considerable differences have been reported in the estimations of China's relative contributions to receptor countries, and higher estimations were usually obtained from studies that focused on short time periods, used outdated emission inventories, and had few or no international collaboration. China's contributions range from 26% to 56% for South Korea and from 13.6% to 53.9% for Japan if the analysis periods are limited to one or several years and the receptors are limited to an entire country. We attributed these differences to the discrepancies in the analysis periods, analytical approaches, modeling settings, definitions of source and receptors, and international collaboration. We also demonstrated that current SRR studies face the challenges from data quality issues in PM measurement data and emission inventories, limited temporal and spatial scales in modeling, and limited analytical perspectives concerning the allocation of environmental responsibilities. Suggestions for future research are provided to address these challenges. [ABSTRACT FROM AUTHOR]

PM2.5 pollution has been a major environmental concern in Chinese cities for the past decade. In order to understand how pollution has proceeded, we produced a calendar view of the daily concentration of PM2.5 in Beijing from 2008 to 2017. The graphic shows that the pollution in Beijing intensified from 2008 to 2011 and then began to alleviate in 2012. The reduction has become more significant since 2015. However, air quality still falls below the international standard for healthy air and it is still early for Beijing to declare victory in the battle against PM2.5. [ABSTRACT FROM AUTHOR]

Fine particulate matter (PM 2.5 ) pollution has been a major issue in many countries. Considerable studies have demonstrated that PM 2.5 pollution is a regional issue, but little research has been done to investigate the regional extent of PM 2.5 pollution or to define areas in which PM 2.5 pollutants interact. To allow for a better understanding of the regional nature and spatial patterns of PM 2.5 pollution, This study proposes a novel framework for delineating regional boundaries of PM 2.5 pollution. The framework consists of four steps, including cross-correlation analysis, time-series clustering, generation of Voronoi polygons, and polygon smoothing using polynomial approximation with exponential kernel method. Using the framework, the regional PM 2.5 boundaries for China are produced and the boundaries define areas where the monthly PM 2.5 time series of any two cities show, on average, more than 50% similarity with each other. These areas demonstrate straightforwardly that PM 2.5 pollution is not limited to a single city or a single province. We also found that the PM 2.5 areas in China tend to be larger in cold months, but more fragmented in warm months, suggesting that, in cold months, the interactions between PM 2.5 concentrations in adjacent cities are stronger than in warmer months. The proposed framework provides a tool to delineate PM 2.5 boundaries and identify areas where PM 2.5 pollutants interact. It can help define air pollution management zones and assess impacts related to PM 2.5 pollution. It can also be used in analyses of other air pollutants. [ABSTRACT FROM AUTHOR]

The Beijing-Tianjin-Hebei area faces a severe fine particulate matter (PM2.5) problem. To date, considerable progress has been made toward understanding the PM2.5 problem, including spatial-temporal characterization, driving factors, and health effects. However, little research has been done on the dynamic interactions and relationships between PM2.5 concentrations in different cities in this area. To address the research gap, this study discovered a phenomenon of time-lagged intercity correlations of PM2.5 time series and proposed a visualization framework based on this phenomenon to visualize the interaction in PM2.5 concentrations between cities. The visualizations produced using the framework show that there are significant time-lagged correlations between the PM2.5 time series in different cities in this area. The visualizations also show that the correlations are more significant in colder months and between cities that are closer, and that there are seasonal changes in the temporal order of the correlated PM2.5 time series. Further analysis suggests that the time-lagged intercity correlations of PM2.5 time series are most likely due to synoptic meteorological variations. We argue that the visualizations demonstrate the interactions of air pollution between cities in the Beijing-Tianjin-Hebei area and the significant effect of synoptic meteorological conditions on PM2.5 pollution. The visualization framework could help determine the pathway of regional transportation of air pollution and may also be useful in delineating the area of interaction of PM2.5 pollution for impact analysis. [ABSTRACT FROM AUTHOR]

Exposure to fine particulate matter (PM) has been associated with mortality, but the extent of the adverse impacts differs across various regions. A quantitative estimation of health effects attributed to PM in China is urgently required, particularly because it has the largest population and high air pollution levels. Based on the remote sensing-derived PM and grid population data, we estimated the acute health effects of PM in China using an exposure-response function. The results suggest the following: (1) The proportion of the population exposed to high PM concentrations (>35 μg/m) increased consistently from 2000 to 2011, and the population exposed to concentrations above the threshold defined by World Health Organization (WHO) (>10 μg/m) rose from 1,191,191,943 to 1,290,562,965. (2) The number of deaths associated with PM exposure increased steadily from 107,608 in 2000 to 173,560 in 2010, with larger numbers in the eastern region. (3) PM health effects decreased in three pollution control scenarios estimated for 2017, i.e., the Air Pollution Prevention and Control Action Plan (APPCAP) scenario, the APPCAP under WHO IT-1 scenario (35 μg/m), and the APPCAP under WHO IT-3 scenario (15 μg/m), which indicates that pollution control can effectively reduce PM effects on mortality. [ABSTRACT FROM AUTHOR]