A Cross-Sectional Analysis of Ambient Fine Particulate Matter (Pm2.5) Exposure and Haemoglobin Levels in Children Aged Under 5 Years Living in 36 Countries

Abstract

Low haemoglobin (Hb) concentrations and anaemia in children have adverse effects on development and functioning, some of which may have consequences in later life. Exposure to air pollution is reported to be associated with anaemia, but there is little evidence specific to low- and middle-income countries (LMICs), where childhood anaemia prevalence is greatest. We aimed to determine if long-term ambient fine particulate matter (≤2.5 µm in aerodynamic diameter [PM2.5]) exposure was associated with Hb levels and the prevalence of anaemia in children aged <5 years living in 36 LMICs. We used Demographic and Health Survey data, collected between 2010 to 2019. Satellite-derived estimates of annual average PM2.5 was the main exposure variable. Anaemia was defined according to standard World Health Organization guidelines (Hb <11 g/dL). The association of PM2.5 with Hb levels and anaemia prevalence was examined using linear and logistic regression models, respectively, and models were adjusted for relevant covariates. We examined whether the effects of PM2.5 were modified by a child’s sex and age, household wealth, and place of residence. The study included 154,443 children, of which 89,904 (58.2%) were anaemic. The country-level prevalence of anaemia ranged from 15.8% to 87.9%. Mean PM2.5 exposure was 33.0 (± 21.6) μg/m3. In the adjusted model, a 10 μg/m3 increase in annual PM2.5 concentration was associated with greater odds of anaemia (OR = 1.098; 95% CI: 1.087, 1.109). The same increase in PM2.5 was associated with a decrease in average Hb levels of 0.075 g/dL (95% CI: 0.081, 0.068). There was evidence of effect modification by household wealth and place of residence, with greater adverse effects in children from lower wealth quintiles and children in rural areas. Exposure to annual PM2.5 was associated with decreased blood Hb levels, and greater risk of anaemia, in children aged <5 years living in LMICs.

Note:
Funding Information: This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Conflict of Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Ethical Approval: Procedures and questionnaires for standard DHS surveys have been reviewed and approved by the ICF Institutional Review Board (IRB). Additionally, country-specific DHS survey protocols are reviewed by the ICF IRB and typically by an IRB in the host country. We obtained permission from ICF-DHS program to use the data, and our secondary analyses were deemed exempt from additional ethical review by The University of Queensland Office of Research Ethics (approval: 2020001013).

Keywords: children, anaemia status, haemoglobin level, Air pollution, developing countries