Temporal and spatial heterogeneity of tropospheric O and NO and health impact analysis in Shaanxi, Gansu, and Ningxia regions of China.

O and precursor pollution in the Shaanxi-Gansu-Ningxia region of China is becoming increasingly severe, and the regional pollution characteristics are also more prominent. To investigate the causes of O and NO pollution and the health impacts of O, the spatial and temporal heterogeneity of O and NO pollution and the health and economic losses in the Shaanxi-Gansu-Ningxia region were analyzed by using a detector with optimal parameters and the BenMAP (Environmental Benefits Mapping and Analysis Program-community Edition) model. The results show that O in the troposphere of Shaanxi, Gansu, and Ningxia showed a "bimodal" distribution from 2005 to 2022, reaching a maximum value of 32.6 DU in 2010, and the change of NO increased first and then decreased in the troposphere, reaching a peak value of 5.2 × 10 molec·cm in 2011. The seasonal variations of O and NO were the highest in winter, the second highest in spring and fall, and the lowest in summer. The high-value area of O was mainly located in the northwest of Gansu. The concentration gradually decreased from northwest to southeast. In contrast, the high-value area of NO was concentrated in the east of Guanzhong Plain and the north of Yulin City, and the overall distribution was high in the east and low in the west. Among the interactions of the nine factors, the interactions of temperature and wind speed, precipitation and wind speed had the highest explanatory power for O changes, with 0.951 and 0.96, respectively, and the interactions of temperature and wind speed, and precipitation and sunshine hours had the highest explanatory power for NO changes, with 0.834 and 0.844, respectively; the interactions among pollutants were weaker than the interactions among meteorological factors. Cardiovascular disease is the leading cause of premature death in the population. The number of premature deaths in the three provinces gradually decreases from 2018 to 2020, and the proportion of health economic loss to GDP also gradually decreases, from 1.55%, 0.82%, and 3.99% to 0.2%, 0.34%, and 2.86%, respectively. This study can provide theoretical references for the control and health impacts of O and NO in Shaanxi, Gansu, and Ningxia regions of China.