Contribution of meteorological conditions to inter-annual variations in air quality during the past decade in eastern china

Abstract

During the past decade, air quality in China has undergone considerable variation, which is mostly attributable to anthropogenic emissions and meteorological conditions. The relative effects of meteorological conditions in eastern China were quantified using the Comprehensive Air Quality Model with Extensions (CAMx) for the period 2007–2016, and the year 2012 was chosen as the reference. In combination with observations of the air quality, the relative contributions of the two factors were identified. Six regions were selected according to their geolocations and regional climatic features. The results showed that meteorological conditions alone may have caused up to 10% of the variation in the mean annual air quality index. These conditions were generally favorable in coastal regions but unfavorable in inland ones, and they usually exerted a greater influence during winter. On average, anthropogenic emissions contributed approximately 70% of the change in PM10 concentration (relative to 2012) during the studied decade, but the contribution ratio varied significantly by region and year. Most regions exhibited lower anthropogenic ratios before 2012, indicating the major effects of anthropogenic emissions on air quality after this year. Furthermore, the considerable improvement in the air quality of these regions was mainly ascribed to reduced anthropogenic emissions. This study provides clear evidence that the air pollution control efforts that have been initiated in China since 2013, such as the Air Pollution Prevention and Control Action Plan (APPCAP), have succeeded in improving the air quality. However, attention must also be directed to the effects of meteorological conditions, which may cause severe pollution episodes even during low levels of emissions; thus, air pollution forecasting and appropriate emergency measures should be implemented in the future.