It is evening in Nairobi’s Mukuru informal settlement, and Lucy is busy preparing meals for her family while her two children work on school assignments. The family live in a one-roomed iron-sheet home. Lucy’s husband arrives home from the food vending business they jointly operate in the area and lights a cigarette as he follows the news on local radio. When Lucy finishes cooking, she puts out the kerosene stove and the room is engulfed by smoke. The smoke makes everyone cough and irritates their eyes, but because of concerns about security and privacy in Mukuru, they would rather keep the door and window closed.

Scenes like these are typical of daily life in the settlement (see video below). Locals like Lucy and her family are usually unaware that inhaling polluted air results in serious long-term health impacts, or that air pollution also causes 670 000 premature deaths per year in Africa.

While this account is fictional, it is closely based on what researchers learned during recent studies carried out by Stockholm Environment Institute (SEI), Africa Population and Health Research Centre (APHRC), University of Nairobi, Muungano wa Wanavijiji, and Centre for Ecology and Hydrology (CEH) in the UK.

Locally produced videos on air pollution are widely screened to educate residents of Mukuru about public health issues. Video: Muungano wa Wanavijiji / YouTube.

The team were investigating how Mukuru residents perceive air pollution and its impacts, as well as engaging local people to take part in the research as “citizen scientists” to measure levels of pollution. The researchers focused on three key air pollutants: particulate matter (PM), ammonia (NH3 )and nitrogen dioxide (NO2).

Most families in Mukuru use biomass (charcoal and firewood) or kerosene for cooking, heating and lighting, and these are associated with high PM emissions. Outdoors, materials like plastics and cloth rags are openly burned. Initial findings indicate levels of particulate matter were high both outside and inside the houses, with peaks observed indoors when people cook their evening meals.

Poor ventilation is also a key issue. When people close windows and doors while cooking, concentrations of pollutants reach dangerous levels. Families with children, pregnant women and elderly people suffer most because the health of these groups are more affected by exposure to high levels of PM.

“Now we understand the cause of many premature deaths and why respiratory diseases such as asthma are so common,’’ said Freshia Njeri, one of the locals involved in the study.

Gathering data and raising awareness

“Appropriate policies and interventions to curb air pollution can only be developed with adequate data, which at the moment is limited, not only in Kenya but the rest of sub-Saharan Africa,’’ said Professor Michael Gatari, Director of the Institute of Nuclear Science and Technology at the University of Nairobi. He added that the emergence and wide deployment of low-cost portable monitoring devices can enable citizens to participate in monitoring air quality in their neighbourhoods.

Freshia, an artist who has lived in the area for more than 10 years, says that being part of the study has given her a better understanding of air pollution and its impacts. She was one of a group of local people who worked with the researchers to assess PM levels using portable monitors called Dylos. The research team trained the group in how to use the devices and in understanding the value of good quality data. The group also worked with researchers and fellow residents to get a better understanding of commonly used types of fuel and the reasons why people choose them, and how these contribute to local air pollution. The PM data were analysed to provide a clear picture of each individual’s exposure to particulate matter.

Members of the group now work to raise awareness about pollution and other environmental challenges in forums within and beyond Mukuru.

Open drains carrying human waste are a major contributor to high ammonia levels in Mukuru. Photo: William Apondo / SEI.

Uncontrolled burning of waste is a major contributor of particulate matter. Photo: William Apondo / SEI

Ammonia and nitrogen dioxide

The study found high levels of nitrogen dioxide (NO2) and Ammonia (NH3) in Mukuru. Levels of Ammonia were especially high across the nine measurement sites, with an average concentration of 45.73 µg m-3  – thirteen times higher than levels recorded at a reference site. Open dumpsites and free-flowing human waste were identified as potential sources of ammonia.

According to Dr Marsailidh Twigg of CEH, studies done in Europe show that ammonia has serious negative effects on sensitive ecosystems and plants, such as peat bogs and lichens, and contributes to the formation of particulate matter. Nitrogen dioxide is also a PM precursor, and affects humans and aquatic health.

Studies like these in Europe have led to policies and regulations to bring down emissions of these air pollutants, as well as sulphur dioxide, methane and ozone, targeting various sectors such as agriculture, transport and power production. There is, however, very limited information on the levels of ammonia and nitrogen dioxide in the urban environment in Kenya, so there is a need to monitor these gases over the long-term.

Research to assess nitrogen and nitrogen compounds in the environment is becoming even more critical in Africa and Asia. The fourth session of the United Nations Environment Assembly (UNEA4) in Nairobi recently passed a resolution for sustainable nitrogen management, and according to Mark Sutton, Project Director at the Center for Ecology and Hydrology, speaking at a session at UNEA4, more investment is needed in data collection, analysis and synthesis to inform integrated policy in Africa and Asia. The recent studies in Nairobi are a step in the right direction.

Dr Philip Osano, SEI Africa Acting Centre Director, said, “The findings have been shared with the Nairobi County Government and have been included in the environment action plan for Mukuru, and in the ongoing process to develop an Air Quality Policy and an Air Quality Action Plan for Nairobi City. The information will also contribute to the National Air Quality Management Strategy that is being prepared by the Ministry of Environment and Forestry.”

(*The co-author of this piece Caroline Wamaitha is accredited as Caroline Njoki with the Media Council of Kenya.)