Household Cooking Fuel Type and Child Anaemia in Sub-saharan Africa: Insights From Demographic and Health Surveys

Childhood anaemia is one of the major public health concerns in low and middle-income countries, contributing substantially to childhood mortality and morbidity. This study, therefore, sought to investigate the association between household cooking fuel type, and the joint impact of household cooking fuel type and urbanicity on anaemia among children under the age of 5 in sub-Saharan Africa. We analysed cross-sectional data of 95,056 children under the age of 5 from 29 sub-Saharan African countries. Bivariate and multivariate analyses were performed using chi-square test of independence and negative log-log regression respectively at p < 0.05. Results were presented as Adjusted Odds Ratios for the negative log-log regression analysis. = 0.955; CI = 0.929–0.981] had lower odds of being anaemic. Our study established an association between the joint effect of type of household cooking fuel and urbanicity and anaemia among children under the age of 5 in SSA. Childs’ birthweight, current age, maternal age, sex of household head, age of household head, maternal education, wealth status, size of household, type of source of drinking water and country of residence are associated with childhood anaemia. It is therefore critical to promote the usage of clean cooking fuels among households and women in rural areas. This could be done by governments in various countries subsidising the cost of liqueed petroleum gases and cylinders. Stakeholders that seek to improve maternal and child health should also take these associated factors into consideration. weight and biosocial factors (Model 2), sociocultural (Model 3), and the contextual (Model 4). Literature and parsimony informed the chosen groups of references for the predictor variables in the models. Respondents from urban settings who rely on unclean cooking fuel types “Unclean urban” was chosen for the key predictor. The selected reference group for sex of child and sex of household head was “male”. Studies show that males in households are often less worried about children under ve years as well as water and sanitation issues (Armah et al., 2018; Mulenga et al., 2017). The selected reference group for current age of child was “0”. Young adults and no education were respective selected as reference groups for age of household head and educational attainment of mother. Unimproved was selected as the reference group for source of drinking water and type of toilet facility. The young adult group was as the reference group because this is a demographic group in transition and may be unable to provide better services for the family while those with no education has direct effect on ability to afford and capacity to spearhead decision-making of households with respect to better services and conditions. Small household size was selected as the reference group for household size.

The associations between household biomass fuel use in cooking and important health variables of women and children such as adverse pregnancy outcomes (low birth weight, stillbirth) (Amega, Quansah & Jaakkola, 2014; Epstein et al., 2013); women health (BMI, anaemia) (Ali, Khan & Feroz, 2020; Amegah, Boachie, Näyhä & Jaakkola, 2019); and the health of children under 5 years of age (child weight, child anaemia) (Kyu, Georgiades & Boyle, 2010; Epstein et al., 2013) have been explored. Few studies have explored the association between household biomass fuel use, a notable source of indoor air pollution in LMICs with child anaemia in SSA. Further, critical to our understanding but absent in such sub-regional analysis by studies is the joint impact of household biomass fuel use and urbanicity on child anaemia in SSA. This study therefore seeks to investigate the joint effect of household biomass fuel use for cooking and urbanicity on anaemia among children under the age of 5 in SSA.

Data Source
Nationally representative data from the Demographic and Health Surveys (DHS) Program for SSA countries from 2010 to 2018 were acquired for analysis in this study. The DHS program provides a large secondary data gathered from surveys using probability sampling methods, following standard protocols that are internationally accepted. Different sets of questionnaires designed and pre-tested to ensure reliability and amenability for comparison of data gathered on various spatial and temporal scales are used in the survey. Some questionnaires the program uses include the "Children's questionnaire" "Mother's questionnaire", "Men's questionnaire" and "Household questionnaire". These questionnaires cover a broad range of variables cutting across demographics and anthropometrics, water and sanitation, health, wealth, nutrition among others. The program recruits and trains eld o cers to collect accurate data and measurement of weight, height, anaemia using recommended guidelines and instruments. Data on other important variables such as household cooking fuel, urbanicity, wealth, water and sanitation are taken at the household level.

Study Countries
A sample of 95,056 was drawn from 29 countries in SSA (show in Fig. 1). For a country to be selected, it must meet the following criteria; should be found in SSA based on the United Nations regional groupings; it must have a DHS dataset with standardized questions and observations on anaemia level of children under ve years as well as household cooking fuel type, urbanicity, source of drinking water and type of toilet facility. Where multiple datasets exist for a country, the most recent dataset is used. Detailed information on countries, together with years of survey are shown in Table 1. De nition Of Important Variables The dataset provided information on household cooking fuel type, source of drinking water and toilet facility type at the household level. The observations for 2.5 kg) and "Normal" (≥ 2.5 kg) (see, Yaya et al., 2019). Also, the observations for household source of drinking water and type of toilet facility were classi ed into "improved" and "unimproved" using the revised de nitions by the WHO/UNICEF Joint Monitoring Programme (JMP) report (World Health Organization & UNICEF, 2017). Table 2 summarises the descriptions of improved and unimproved sources of water and toilet facilities. Armah et al. (2018) further explicates the categorisation of these critical basic services. Anaemia status of children is the outcome variable considered in this study. According to DHS, the anaemia status of living children within the age bracket 0-4 years before the survey night was taken. It has its responses classi ed into four (4) categories according to the WHO recommendation as: (i) "Not anaemic" for children with hemoglobin count(g/dl) measuring above 11 g/dl; (ii) "Mild anaemia" for hemoglobin count of 10-10.9 g/dl; (iii) "Moderate anaemia" for hemoglobin count between 7.0-9.9 g/dl; and (iv) "Severe anaemia" for hemoglobin count less than 7.0 g/dl. Children with no observations for anaemia count (not tested), and those whose mothers were not listed in the household questionnaire were excluded. Observations under mild, moderate and severe were combined and recoded as "Anaemic (Yes)" and observations under not anaemic was recoded as "Not anaemic (No)". The Anaemia status of children was represented as a dichotomous variable with "0" representing "No" and 1 representing "Yes"

Main Predictor Variable
The predictor chosen for this study is a composite variable formed from the interactive effect of household cooking fuel type and urbanicity. The selection of the predictor variable was based on parsimony, literature review, theoretical relevance as well as practical signi cance. Household cooking fuel type and Urbanicity both had two categories, since the former was classi ed into "Clean" and "Unclean" and the latter measured as "Rural" and "Urban" per the Demographic Health Survey (DHS). This therefore gave a four mutually exclusive groups: Unclean urban (households relying on "unclean" cooking fuel and found in urban areas); Unclean rural (households relying on "unclean" cooking fuel and found in rural areas); Clean urban (households using "clean" cooking fuels and found in urban areas); and clean rural (households using "clean" cooking fuels and found in rural areas).
The study considered socio-cultural factors including: educational attainment of mother (no education, primary, secondary, tertiary); birth order number (1, 2, 3, 4, 5 and above); household size (small: 1-5, medium: 6-10, large: above 10). Also, the DHS collects data on wealth index of all interviewed households and place them into ve wealth quintiles (poorer, poor, middle, rich, richer). Observations of wealth index under poorer and poor were combined and recoded as "poor". Similarly, observations under "rich" and "richer" were combined and recoded as "rich". Finally, household source of drinking water and type toilet facility which were both categorized into "improved" and "unimproved".
According to studies ( The Stata 14 MP software was used for the analysis of data. To understand the distribution of childhood anaemia and in uence of predictive factors on anaemia, descriptive analysis was performed. We then determined the associations between anaemia status of children under ve and the relevant predictors using inferential statistics. These relationships were further examined using multivariate techniques while controlling for theoretically relevant compositional and contextual factors. Statistical signi cance of 0.05 and 95% con dence interval (CI) were used in analysis and results presented as contingency tables.

Univariate Analysis
Pearson chi-square test of independence and Cramer's V statistic were applied in the univariate analysis of predictors of child under ve anaemia. The strength of associations between anaemia status and the predictors was tested using Cramer's V statistics.

Multivariate Regression
The outcome variable (anaemia status of children under age 5) had 57% of responses in the non-a rmative and 43% were a rmative. The relationship between anaemia status and the interactive effect of household cooking fuel and urbanicity was analysed using negative log-log regression model. A negative log-log regression model is apt when the responses to a dichotomous response variable is asymmetric in the [0, 1] interval for which the non-a rmative is more than 55% as in the case of the response variable in this study (Aitkin et  . The likelihood of a child been anaemic was estimated and reported as exponential coe cients -odds ratios (OR). An OR of 1 means that the predictor does not affect the odds of a child been anaemic; OR > 1 means that the predictor is associated with higher odds of been anaemic; and OR < 1 means that the predictor is associated with lower odds of been anaemic. Clustering of observations in units of households was controlled by imposing on the models a "cluster" variable, thus, the identi cation numbers of the respondents at the cluster level. This adjusted the SE leading to statistically robust estimation of parameters.
At the multivariate level, four (4)  . The selected reference group for current age of child was "0". Young adults and no education were respective selected as reference groups for age of household head and educational attainment of mother. Unimproved was selected as the reference group for source of drinking water and type of toilet facility. The young adult group was selected as the reference group because this is a demographic group in transition and may be unable to provide better services for the family while those with no education has direct effect on ability to afford and capacity to spearhead decision-making of households with respect to better services and conditions. Small household size was selected as the reference group for household size.

Ethical Considerations
The DHS Program recognizes and adheres to established international and local ethical standards and protocols in its surveys. The ICF International's Institutional Review Board (IRB) through The DHS Program's reviewed and approved all survey procedures and instruments used before implementation. The board aside providing technical assistance to the program ensures that the survey complies with the United States Department of Health and Human Services regulations for the protection of human subjects CFR 46 as well as the laws of the individual countries.

Descriptive analysis
The study included 95,056 children under the age of 5 years from 29 SSA countries. The percentage of children who suffered anaemia was 57% while those who were not anaemic accounted for 43%. A majority (57%) of the children included in the survey were in rural households that used unclean cooking fuels.
The results indicate that only 13% of children under the age of 5 years are from household that rely on clean cooking fuel whiles 87% lived in households using unclean cooking fuels. Further, prevalence of anaemia was highest (59%) among children in urban households that use unclean cooking fuels, and rural households that use cleaning cooking fuels. Even though a majority of children were in households with improved source of drinking water (75%); and improved toilet facility (54%), most of these children, 58% and 60% respectively suffered anaemia. Child anaemia is high (60%) among children in rich households, which constitute a slightly higher percentage (41%) of households by wealth status. Even though a relatively high percentage (35%) of children included in the study were in rural households of poor wealth status, a majority (59%) of children from rich households in rural areas were anaemic. On educational attainment of mothers, only a few children (4%) belonged to mothers who had tertiary education, most (65%) of whom were anaemic.
Notwithstanding the relatively few children from Namibia (1%) and Rwanda (4%) included in the survey, each recorded 82% child anaemia. Despite accounting for only 4% of the children studied, Benin recorded the least (31%) prevalence of child anaemia. Categorizing the countries into their geographical location, we found that, of the 17% and 18% of children from Southern Africa and Central Africa, 74% of children each region suffered anaemia.
The probability (P) value of all variables except sex of child were signi cant. The Pearson Chi-squared analysis therefore rejects the null hypotheses that anaemia level is independent of source of drinking water and toilet facility as well as compositional and contextual factors. These results therefore signify that household source of drinking water and type of toilet facility affect anaemia level of children under ve years old. Again, the P-values show that the gures obtained for anaemia level were not by chance and if the analyses were repeatedly run, same results would be obtained. Cramer's v statistics however shows weak to moderate associations between the key predictor, compositional and contextual factors. The contingency Table 3 shows the detailed results.   Table 4).

Discussion
In this current study, our principal aim was to investigate the association between household biomass fuel use, and the joint effect of household biomass fuel use for cooking and urbanicity on anaemia among children under the age of 5 in SSA. The study showed that children from rural households that depend on unclean cooking fuels were more likely to be anemic compared with children from urban households using unclean cooking fuel. This is in line with previous studies in various parts of the world such as Timor-Lest (Pinto, 2016) and India (Page, Patel, & Hibberd, 2015;Baranwal, Baranwal, & Roy, 2014). Although this study was a cross-sectional study and could not claim causality, some studies (Page, Patel, & Hibberd, 2015) have explained that exposure to unclean cooking fuels may lead to systemic in ammation which is regarded as a popular cause of anaemia, mediated by in ammatory cytokines such as tumor necrosis factor alpha (TNF-α), interleukin-1 (IL-1), interleukin-6 (IL-6), and interferon-γ (IFN-γ) ( Weiss & Goodnough, 2005). The pathways by which these causes anaemia include dysregulation of iron homeostasis, impaired erythropoietin response to reduced hemoglobin levels, and impaired marrow response to erythropoietin (Weiss & Goodnough, 2005;Page, Patel, & Hibberd, 2015). Apart from the key independent variable, we controlled for other key factors associated with anaemia among children under ve which are worth discussing in light of previous evidence.
We found that the birthweight of the child had statistically signi cant association with anaemia. Speci cally, children with normal weight had lower odds of being anemic compared with underweight children. This is in consonance with previous studies in Ethiopia (Gebreegziabiher, Etana & Niggusi, 2014) and Brazil (Santos et al., 2011). Some previous studies espoused that there is a direct link between food consumption and anaemia. Another major nding in our study was that the odds of suffering from anaemia decreased with age of the child. This nding is supported by other studies had the lowest odds of being anemic. This is consistent with previous studies in Ethiopia (Asresie, Fekadu & Dagnew, 2020). It is possible that as mothers advance in age, they gain experiences with childcare and also, they are more likely to be exposed to education on appropriate practices on childhood nutrition compared with those who are adolescents. In line with a previous study (Engidaye et al., 2019), we also found that children in female headed households, middle aged adults, old age adults were more likely to be anemic compared with those in male headed households; and households headed by young adults.
Surprisingly, our study showed that children in households with improved source of drinking water had higher odds of being anaemic. This is contrary to other

Strengths And Limitation
The major strength of this study is the use of recent nationally representative surveys, with relatively large sample sizes. This makes the ndings generalisable to all under ve children in the countries we included in our study. In addition, we employed rigorous statistical modelling to assess the association between the type of cooking fuel and anaemia while controlling for theoretical and practical confounders. The study however, is limited by the cross-sectional nature of the design employed for the data collection. Due to this, it is impossible to detect temporality of sequence. Also, geographic region and Urbanicity Wealth were associated with child anaemia (p < 0.05) but could not be included in the model due to multicollinearity.

Conclusion
Our study found that there is an association between the joint effect of household biomass fuel use for cooking and urbanicity and anaemia among children under the age of 5 in SSA. Apart from this we also found that birthweight of the child, age of the child, maternal age, sex of household head, age of household head, maternal education, wealth status, size of household, type of source of drinking water and country of residence are associated with childhood anaemia.
The following recommendations are therefore made for policy and practice. Firstly, it is critical to promote clean fuel usage among households and women in rural areas. This could be done by governments in various countries by enhancing access and subsidising the cost of natural and or, liqui ed petroleum gas Figures Figure 1 Map of study countries with spatial representation of child under age 5 anaemia Figure 1 Map of study countries with spatial representation of child under age 5 anaemia