Background concentrations of PMs in Xinjiang, West China: An estimation based on meteorological filter method and Eckhardt algorithm

Quantitative evaluation of background concentrations of pollutants in atmospheric field can help us implement effective measures to improve air quality. The aim of this study was to estimate background concentrations of PM10 and PM2.5 in Xinjiang using meteorological filter and the Eckhardt algorithm. In this study, the meteorological factors including wind direction, wind speed and temperature were used to filter the background periods. Results showed that annual average background concentrations of PM10 and PM2.5 in Xinjiang were 112 μg/m3 and 39 μg/m3 in 2016, respectively. There were seasonal differences on background concentrations of PMs in Northern and Southern Xinjiang, and the background concentrations in Southern Xinjiang were much higher than those in Northern Xinjiang. Background concentrations from easterly wind (49 μg/m3 for PM10 and 29 μg/m3 for PM2.5) and westerly wind (179 μg/m3 for PM10 and 63 μg/m3 for PM2.5) were the highest in Northern Xinjiang and Southern Xinjiang, respectively. Dust from Taklimakan Desert had great contribution to the background concentrations of PMs in Southern Xinjiang area. Good correlations were obtained when comparing the two methods. The differences of annual average background concentrations in Xinjiang between two methods were 9 μg/m3 for PM10 and 4 μg/m3 for PM2.5. The estimated background concentrations by the proposed method can be used by local government to develop more efficient pollution control policies.