Spatio-Temporal Characteristics of Air Quality Index (AQI) over Northwest China

In recent years, air pollution has become a serious threat, causing adverse health effects and millions of premature deaths in China. This study examines the spatial-temporal characteristics ambient quality five provinces (Shaanxi (SN), Xinjiang (XJ), Gansu (GS), Ningxia (NX), Qinghai (QH)) northwest China (NWC) from January 2015 to December 2018. For this purpose, surface-level aerosol pollutants, including particulate matter (PMx, x = 2.5 10) gaseous pollutants (sulfur dioxide (SO2), nitrogen (NO2), carbon monoxide (CO), ozone (O3)) were obtained National Environmental Monitoring Center (CNEMC). The results showed that fine (PM2.5), coarse (PM10), SO2, NO2, CO decreased by 28.2%, 32.7%, 41.9%, 6.2%, 27.3%, respectively, while O3 increased 3.96% NWC during 2018 as compared with 2015. (PM2.5 PM10) levels exceeded Chinese Ambient Air Quality Standards (CAAQS) Grade II standards well WHO recommended Guidelines, SO2 NO2 complied CAAQS NWC. addition, average index (AQI), calculated ground-based data, improved 21.3%, proportion Class I (0–50) 114.1%, number days 61.8% All pollutants’ (except ozone) AQI PM2.5/PM10 ratios highest winter lowest summer. was strongly positively correlated PM2.5, PM10, CO, negatively O3. PM10 primary pollutant, followed O3, different spatial temporal variations. but for provides useful information valuable reference future research on