Determinants of Carbon Load in Airway Macrophages in Pregnant Women

Background: The available evidence on determinants of personal exposure to air pollution in low and middle-income countries is very scarce. Moreover, although airway macrophages carbon loading (AMCL) has been suggested to be a biomarker of the long-term exposure to air pollution, to date no study has characterized AMCL for the pregnancy period. Therefore, this study aimed to assess the determinants of AMCL during pregnancy in Iran, a middle-income country. Methods: This study was based on a sample of 234 pregnant women with term and normal vaginal delivery who were residing in Sabzevar, Iran (2019). Image analysis was applied to calculate the carbon area (µm 2 ) in airway macrophages as an indicator of AMCL. For each participant, we characterized 35 potential determinants of personal exposure to air pollution including six personal, nine indoor, and 20 home-outdoor factors. We applied Deletion/Substitution/Addition algorithm to identify the most relevant determinants that could predict AMCL levels. Findings: The median (IQR) of AMCL level was 0·12 (0·30) µm 2 with a successful sputum induction in 82·9% (194) of participants. Ambient residential PM 2·5 levels was positively associated with higher AMCL levels. On the other hand, increased residential distance to the traffic lights, squares and ring-roads, the duration of opening window per day, and opening window during cooking were inversely associated with AMCL levels. Interpretation: Our findings provide novel insights on the different personal, indoor, and outdoor determinants of personal exposure to air pollution during pregnancy in a middle-income country. Funding: This study was supported by a research grant awarded by the Sabzevar University 55 of Medical Sciences [Grant number: 95075]. Declaration of Interest: We declare no competing interests. Ethical Approval: The Clinical Research Ethical Committee of Sabzevar University of Medical Sciences approved our study (IR.MEDSAB.REC.1395.82)