Understanding the association of individual pollutants with pneumonia episodes in children under five in Abuja, Nigeria

Adaji, Enemona (2021) Understanding the association of individual pollutants with pneumonia episodes in children under five in Abuja, Nigeria. PhD thesis, University of Nottingham.

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Pneumonia kills nearly one million children under the age of five globally, every year. Despite reductions in global pneumonia mortality, progress in the highest-burden countries remains slow. 60% of all pneumonia fatalities occur in 10 countries of which Nigeria is currently number one overtaking India. Equally, air pollution remains a major public health concern worldwide. Globally air pollution is responsible for over 7 million deaths annually. Exposure to high levels of pollution is constantly on the rise, especially in urban cities. Exposure to air pollution alters lung health in many ways leading to the exacerbation of respiratory illnesses. Consequently, this would increase the risk of developing pneumonia especially in vulnerable populations such as children where the respiratory tract is still underdeveloped.

Several reviews have been published looking at the effect of indoor air pollution and the effect this has on pneumonia in children. However, there was no standard assessment for exposure across studies. Also, a combination of different study designs, sample sizes, follow up period and dose-response makes the conclusions hard to interpret. Indoor concentrations of carbon monoxide (CO), particulate matter (PM), and more recently black carbon (BC) concentrations have been associated with respiratory infections in children. Unfortunately, the current understanding of the association of indoor air pollution on pneumonia in children under five is, inconclusive and only partially understood. This study aims to plug this important gap in the literature and is the first study investigating the association of individual pollutant components (PM1, PM2.5, CO and Black Carbon) and childhood pneumonia in Abuja Nigeria using primary field observations.

Objective: To investigate the impact of indoor air pollution on childhood pneumonia episodes in Abuja, Nigeria, the key aims of this study were;

1. To undertake a systematic literature review (Published).

2. To identify areas with a higher incidence of pneumonia and high pollution exposure in Nigeria using the 2013 Demographic Health Survey (DHS) data (under review Environmental Health Perspectives).

3. To investigate the association between PM (1 and 2.5), CO and BC and pneumonia episodes in children under five (under review Environmental Health and Pollution Research).

4. To explore health professionals’ perspectives on the effect of household air pollution and childhood pneumonia episodes. Exploring, strengths, weaknesses, gaps and opportunities within the healthcare system (manuscript under preparation).


Secondary data analyses included the national and subnational representative data from Nigeria obtained from the 2013 round of the Demographic Health Survey (DHS) was used for air pollution and ARI hotspot identification. Furthermore, primary data collection used a mixed-method approach case-control (quantitative) and key informant interviews (qualitative) to assess the effects of air pollution and pneumonia in children under-five. The case control study measured PM2.5, CO, BC and PM1 using PATS+, a phone-based system developed by NEXLEAF ANALYTICS and SidePak Personal Aerosol Monitor AM510 (TSI Inc, MN, USA) in 150 cases and 140 controls. Semi-structured interviews were conducted with 19 healthcare professionals. Quantitative data was managed and analysed using STATA TM 16, whilst qualitative data was managed and analysed with NVivo TM 12.


Secondary data analyses from the 2013 DHS in Nigeria indicated that biomass fuel and improved housing were positively associated with ARI. Being exposed to biomass fuel increased the risk of ARI by 55% in children under five. The results of the STAR model showed that living in an improved house has a protective effect against ARI and reduces the risk of ARI by 28%. The risk maps showed that more than half of the children under five population were at increased risk for acquiring ARI due to burning of biomass fuel and emitted PM2.5. Furthermore, the Nigerian population subject to high levels of air population also showed a treatment-seeking rate of less than 50% in cases of fever.

Primary data from the case control study indicates that the mean PM2.5 was higher in control households compared to cases households. PM2.5 highest mean recorded for controls was 177 µg/m3 and 129 µg/m3 for cases. There was a significant difference between cases and controls for 10 hours (p-value 0.0147), 15 hours (p-value 0.0111) and 20-24 hours (p-value 0.0296) for PM2.5.

No significant difference in CO concentration was observed between cases and controls, the highest CO mean concentration recorded being 2930 µg/m3. Similarly, PM1 was consistently higher in controls compared to cases. However, this difference was not significant from exposure to PM1 between cases and controls (p-value>0.05), with the highest PM1 mean concentration recorded being 91 µg/m3.

There was a significant difference (p-value 0.0260) in exposure to Black Carbon (BC) between cases and controls. BC was higher in households of cases compared to controls, with the mean average of BC for cases 4350 µg/m3 and controls 4126 µg/m3. In this study, BC was positively associated with a pneumonia episode. We also report the importance of unmodifiable and behaviourally modifiable factors on pneumonia episode in children.

Finally, key informants interviews with healthcare professionals provides a deeper insight into the perception of household indoor air pollution and childhood pneumonia amongst these stakeholders. Healthcare professionals complained of the lack of funding to the lack of equipment and support needed for the treatment of their patients. Also, lack of awareness regarding health risks from household air pollution, level of education, poverty, treatment-seeking behaviour, lack of research and funding and effective implementation of policies were amongst the themes that emerged from the interviews with frontline healthcare experts.


Pollution is widely investigated using proxy indicators for pollutants in developing countries. Also, pollutant components such as PM2.5, PM1, BC and CO are often investigated in isolation. Therefore, the gap still exists for the simultaneous measurement of key pollutants in association with pneumonia.

Biomass fuel and PM2.5 increase the risk of ARI in under five children in Nigeria. Strategies to reduce air pollution exposure and increase treatment seeking should be explored as a means to reduce the disease burden and potentially ARI related mortality in under five children in Nigeria.

We show that children present during cooking, number of available windows and MUAC showing red all increased the likelihood of a pneumonia episode. We recommend household level behaviour changes and targeted IMCI including early effective detection and treatment of childhood pneumonia particularly in high pollution areas in Nigeria.

This research is particularly important as a starting point for policy review since the vast majority of affected countries like Nigeria with high childhood pneumonia mortality and morbidity have difficulty implementing their current laws or policies needed to guide both national responsibilities and international engagements in tackling childhood pneumonia. Evidence presented in this research revealed the context of this, from the Nigerian perspective by providing nationwide hotspot maps. Although focused on only one country, the findings of BC being associated with pneumonia episodes have a broader relevance as indoor air pollution and childhood pneumonia challenges inevitably contribute to similar health and social burdens worldwide.

Item Type: Thesis (University of Nottingham only) (PhD)
Supervisors: Phalkey, Revati
Clifford, Michael
Keywords: Pneumonia; Indoor air pollution; Pollutants; Children
Subjects: W Medicine and related subjects (NLM Classification) > WA Public health
W Medicine and related subjects (NLM Classification) > WS Pediatrics
Faculties/Schools: UK Campuses > Faculty of Medicine and Health Sciences > School of Medicine
Item ID: 64667
Depositing User: Adaji, Enemona
Date Deposited: 31 Jul 2021 04:40
Last Modified: 31 Jul 2021 04:40
URI: http://eprints.nottingham.ac.uk/id/eprint/64667

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