Abstract
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)
Highlights
Air pollution is a major environmental hazard worldwide
Whilst studies on determinants of the personal exposure to air pollution could provide an evidence base necessary to fine-tune targeted interventions to tackle the burden of air pollution, a vast majority of these studies have been conducted in high-income countries whose finding are not necessarily generalizable to LMICs, for which such evi dence is still very scarce
If the results of carbon loading measurements for each participant were exactly similar between the two raters, we reported this value as the final airway macrophages carbon loading (AMCL) level for that sample
Summary
Air pollution is a major environmental hazard worldwide. More than 98% of the global population lives in areas that do not meet World Health Organization (WHO) air quality guidelines and, at the same time, there is a notable difference between high-, middle-, and low-income countries in this regard (WHO, 2021). In high-income coun tries, about half of the cities with a population of more than 100 000 inhabitants do not meet WHO air quality recommendations, this pro portion reaches 97% in low- and middle-income countries (LMICs) cities. This difference in air pollution levels is accompanied by a considerably greater health burden of air pollution in LMICs. More than 90% of the annual 4.2 million premature deaths that could be attributed to air pollution worldwide, occur in LMICs (WHO, 2021). Whilst studies on determinants of the personal exposure to air pollution could provide an evidence base necessary to fine-tune targeted interventions to tackle the burden of air pollution, a vast majority of these studies have been conducted in high-income countries whose finding are not necessarily generalizable to LMICs, for which such evi dence is still very scarce
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