Recent intensification of winter haze in China linked to foreign emissions and meteorology

Yang Yang,Hailong Wang,Steven J Smith,Po-Lun Ma,Philip J Rasch,Sijia Lou,Rudong Zhang,Yun Qian

doi:10.1038/s41598-018-20437-7

Yang Yang, Hailong Wang + Show 6 more

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https://doi.org/10.1038/s41598-018-20437-7

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Abstract

Wintertime aerosol pollution in the North China Plain has increased over the past several decades as anthropogenic emissions in China have increased, and has dramatically escalated since the beginning of the 21st century, but the causes and their quantitative attributions remain unclear. Here we use an aerosol source tagging capability implemented in a global aerosol-climate model to assess long-term trends of PM2.5 (particulate matter less than 2.5 μm in diameter) in the North China Plain. Our analysis suggests that the impact of China’s increasing domestic emissions on PM2.5 concentrations over the last two decades of 20th century was partially offset (13%) by decreasing foreign emission over this period. As foreign emissions stabilized after 2000, their counteracting effect almost disappeared, uncovering the impact of China’s increasing domestic emissions that had been partially offset in previous years by reductions in foreign emissions. A slowdown in the impact from foreign emission reductions together with weakening winds explain 25% of the increased PM2.5 trend over 2000–2014 as compared to 1980–2000. Further reductions in foreign emissions are not expected to relieve China’s pollution in the future. Reducing local emissions is the most certain way to improve future air quality in the North China Plain.

Highlights

Wintertime aerosol pollution in the North China Plain has increased over the past several decades as anthropogenic emissions in China have increased, and has dramatically escalated since the beginning of the 21st century, but the causes and their quantitative attributions remain unclear
The inverse value of visibility, which is closely related to light extinction, is a good measure of light attenuation caused by aerosols
By isolating the influence of meteorology using normalized emission contributions, we estimate that foreign emissions had less effect on 2000–2014 trends than in 1980–2000 in these seasons

Summary

Introduction

Wintertime aerosol pollution in the North China Plain has increased over the past several decades as anthropogenic emissions in China have increased, and has dramatically escalated since the beginning of the 21st century, but the causes and their quantitative attributions remain unclear. In January 2013, Beijing, the country’s capital and major city in the North China Plain, was hit by severe and persistent haze events[5], with the maximum daily PM2.5 concentration exceeding 500 μg m−3, leading to Beijing’s first haze orange alert in history[6] Exposure to these fine particles harms respiratory and cardiovascular systems, causing morbidity and mortality[7,8,9]. Meteorological conditions play an important role in mixing and advecting pollutants, increasing local aerosol emission from human activities is generally considered to be the dominant cause of increasing wintertime haze over China in past decades[29]. Aerosols in the North China Plain partly arise from emissions from other regions of China and transboundary transport from foreign countries/regions

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