Dr Marsailidh Twigg, an atmospheric chemist at the UK Centre for Ecology & Hydrology (UKCEH), explains the results of an international study, which for the first time provides evidence of the link between lung health and air pollution exposure of schoolchildren in Sub-Saharan Africa. 

Asthma accounts for high levels of illness and mortality in low- and medium-income countries but the condition often goes undiagnosed and untreated in children, particularly in poorer areas.

This was highlighted in a recent study in Kenya by an international research team including UKCEH scientists. It was led by the Kenyan Medical Research Institute (KEMRI) and the Liverpool School of Tropical Medicine (LSTM).

We provided evidence that children in informal settlements are more likely to have an increased risk of asthmatic symptoms that are also more severe compared to children living in more affluent areas. The research also showed, for the first time, that this risk is associated with a child’s exposure to indoor and outdoor air pollution.

The study was part of a large international collaborative project called Tupumue, which is from the Swahili for “let us breathe”. It aimed to investigate the link between air pollution exposure and lung health in schoolchildren from two residential areas of Nairobi: Mukuru, an informal settlement and Buruburu, a more affluent gated community. The project was co-developed with these two communities.

Local parents and children provided input into the study design, data collection and communications through a series of workshops and art-based projects. 

UKCEH scientists were part of the air quality expert team within the project. We trained field workers in Mukuru and Buruburu who undertook the air quality measurements in people’s homes, schools or local meeting places. We also carried out data analysis to evaluate the performance of the particulate matter (PM) sensors and the mapping of the spatial distribution of PM across the two areas.

The study found that air pollution levels in the informal settlement of Mukuru were on average, almost twice as high as Buruburu – 39 micogrammes per m3 compared to 22 microgrammes per m3. The World Health Organization’s recommended safe level is 15 micogrammes per m3 (24 hour average). 

In total, more than 2,000 children from Mukuru and Buruburu took part in tests to establish how many had asthmatic symptoms. The study found that more children in Mukuru had reported wheezing symptoms or lung infections than Buruburu but a lower percentage were diagnosed with asthma or had treatment compared to the more affluent neighbourhood.

Globally up to 500 million children are estimated to be living within informal settlements and our findings indicate that they have an increased risk of developing asthma due to air pollution.

Further information

The Tupumue project was funded by the Medical Research Council and the Kenya National Research Fund (NRF): UK-Kenya Joint Partnership on Non-Communicable Disease programme under the Newton fund (MR/S009027/1). 

An open access paper was published in the BMJ journal Thorax, DOI: 10.21428/3d48c34a.09447715

A documentary, available on YouTube, summarises the methods and findings of the study.