Work

Human mobility-associated ambient PM 2.5 differences and inequality in China

Year: 2026

Type: article

Abstract: Ambient PM 2.5 conditions can differ between origins and destinations during both long-term migration and short-term population mobility, but the magnitude and heterogeneity of these differences remain unclear. Here we quantify migration- and mobility-associated differences in ambient PM 2.5 concentrations in China using a nationally representative survey of ∼170 000 internal migrants and daily inter-city mobility flows derived from Baidu location-based services. We further examine socioeconomic associations using linear regression model. Overall, the survey-weighted mean origin–destination (OD) PM 2.5 difference was −3.29 μ g m −3 , and 57.15% of migrants moved to destinations with lower PM 2.5 concentrations. Migration-associated PM 2.5 differences showed substantial heterogeneity by migration type, distance and household income, with moves to lower-PM 2.5 destinations more common among inter-provincial, longer-distance and higher-income migrants. Regression models further showed that moving to economically stronger destinations did not necessarily correspond to more favorable PM 2.5 differences. At the daily scale, mobility-associated OD PM 2.5 differences shifted markedly during the Spring Festival travel season and followed a regular weekly cycle during non-holiday periods. These findings highlight the importance of considering mobility patterns and their heterogeneity when characterizing population distributions across different ambient pollution environments.

Source: Environmental Research Letters

DOI: 10.1088/1748-9326/aeb683

Authors: Heming Bai, Minghuai Wang, Jing Wei, Steve H L Yim, Dasa Gu, Yang Cao