A health risk-based threshold method to evaluate Urban Atmospheric Environment Carrying Capacity in Beijing-Tianjin-Hebei (BTH) Region

Urban atmospheric environment protection is an important strategy for sustainable urban development. Nevertheless, serious atmospheric pollution problems caused by socioeconomic activities have become a global issue, which brings enormous pressure on human health. However, as the core of urban sustainability, the human health risk is not adopted as an element to evaluate the Urban Atmospheric Environment Carrying Capacity (UAECC) in previous studies. Therefore, this study develops an improved threshold method called the health risk-based threshold method to evaluate UAECC, by adding the principle of the Air Quality Health Index (AQHI) into the traditional threshold method. The effectiveness of the novel UAECC method is demonstrated by using the data collected from a sample of 13 cities in the Beijing-Tianjin-Hebei (BTH) region. Moreover, the case demonstration considers both the microscopic and macroscopic UAECC. The demonstration results suggest that (1) poor performance of UAECC happens in urban built-up areas; (2) the UAECC performance of cities located in the north part of BTH region behaves better than that in the south part; (3) PM2.5, PM10, and NO2 are three primary contributors to the UAECC performance in the BTH region; (4) the UAECC performance in the BTH region has been improved, while the single-factor of O-3 deteriorated from 2015 to 2020. Furthermore, the evaluation results by using the improved method can provide valuable references for formulating tail-made policies towards different cities with different UAECC conditions.