Understand the local and regional contributions on air pollution from the view of human health impacts

* PM 2.5-related deaths were estimated to be 227 thousand in BTH & surrounding regions. * Local emissions contribute more to PM 2.5-related deaths than PM 2.5 concentration. * Local controls are underestimated if only considering its impacts on concentrations. * Rural residents suffer larger impacts of regional transport than urban residents. * Reducing regional transport benefits in mitigating environmental inequality. The source-receptor matrix of PM 2.5 concentration from local and regional sources in the Beijing-Tianjin-Hebei (BTH) and surrounding provinces has been created in previous studies. However, because the spatial distribution of concentration does not necessarily match with that of the population, such concentration-based source-receptor matrix may not fully reflect the importance of pollutant control effectiveness in reducing the PM 2.5-related health impacts. To demonstrate that, we study the source-receptor matrix of the PM 2.5-related deaths instead, with inclusion of the spatial correlations between the concentrations and the population. The advanced source apportionment numerical model combined with the integrated exposure-response functions is used for BTH and surrounding regions in 2017. We observed that the relative contribution to PM 2.5-related deaths of local emissions was 0.75% to 20.77% larger than that of PM 2.5 concentrations. Such results address the importance of local emissions control for reducing health impacts of PM 2.5 particularly for local residents. Contribution of regional transport to PM 2.5-related deaths in rural area was 22% larger than that in urban area due to the spatial pattern of regional transport which was more related to the rural population. This resulted in an environmental inequality in the sense that people staying in rural area with access to less educational resources are subjected to higher impacts from regional transport as compared with their more resourceful and knowledgeable urban compatriots. An unexpected benefit from the multi-regional joint controls is suggested for its effectiveness in reducing the regional transport of PM 2.5 pollution thus mitigating the associated environmental inequality.