Context and rational
Air pollution is a major environmental public health problem. In 2012, according to the WHO, 8 million premature deaths worldwide from chronic respiratory diseases, lung cancer, stroke and heart disease were caused by air pollution, including 3.7 million from outdoor pollution and 4.3 million from indoor pollution (WHO, 2012). In developing countries, air pollution is also a major contributor to the onset and aggravation of chronic obstructive pulmonary disease (COPD), and to the onset of acute and chronic respiratory illnesses in children.
Outdoor air pollution caused by vehicles, industry and rapid urbanization exposes the population to high concentrations of particulate matter (PM) with a diameter of 2.5 µm or less (PM2.5). PM increases the risk of cardiovascular disease, acute (pneumonia) and chronic respiratory illnesses, primarily COPD, as well as impairment of lung function in children and exacerbation of asthma (WHO, 2016). Moreover, indoor air pollution, which is also a major source of inhalation of respiratory pollutants, constitutes a major and additional health risk for people exposed to the use of combustion energy from biomass, such as wood, charcoal, crop waste, and kerosene for cooking, especially children, thus increasing the risk of pneumonia (WHO, 2018).
Children are particularly at risk of pollution-related respiratory diseases. They have a heightened sensitivity to air pollutants, exhibiting increased particle deposition in the lungs due to physiological and anatomical factors at a key period of lung development. Children’s environmental exposure to pollution during periods of lung growth and development can lead to irreversible long-term deficits in lung function, and put adults at high risk of COPD. In 2016, approximately 543,000 deaths of children under 5 years of age and 52,000 deaths of children aged 5 to 15 years were attributable to indoor and outdoor air pollution. Exposure to indoor air pollution increases the risk of childhood pneumonia by almost 2-fold, and is responsible for 45% of pneumonia deaths among children under 5 years of age (6). In low- and middle-income countries, air pollution (indoor and outdoor) causes more than 50% of acute lower respiratory tract infections in children under five.
The health effects of ambient air pollution are understudied in Africa compared to other continents. Few studies evaluate the association between air pollution and negative health effects, and most sub-Saharan African countries have no available data on pollution. As a result, the majority of large African cities are not equipped with pollution level sensor networks or warning systems. Knowledge and perception of pollution risks are still very limited.
In cities such as Abidjan (Côte d’Ivoire), urbanization has not curbed the use of biomass combustion for cooking and traditional fish smoking. This activity is particularly harmful to the health of these women and their children, as they are exposed repeatedly and intensively to smoke and heat.
Indoor sources may co-emit APECs along with regulated1 air pollutants (RAPs) which are also known to have a negative impact on respiratory health (decrease in lung function, asthma exacerbation, lower tract infections), and suggested impact on the respiratory health of new-borns after in-utero exposure (11). Gas stoves for instance, which are the main cooking appliance for 20%-68.5% of the population in 13 of the 27 EU-member countries(12), emit both UFPs and NO2 among other pollutants. This points to a need to study APECs jointly with classical regulated air pollutants such as NO2 or PM2.5 in the case of asthma.
Household air pollution (HAP) is therefore a major source of population exposure to both APEC and RAPs with demonstrated or hypothesized impacts on lung health, notably in children and adolescents. HAP exposure could in particular be reduced thanks to individual behaviour change if people had access to information, to individual monitoring devices, and to alternative technical solutions to replace polluting devices. With the emergence of new tools such as low-cost sensors for user-friendly HAP measurements and recent progress in involving citizens in participatory research, there is an opportunity to develop innovative approaches based on citizen science to conduct research on the impacts and mitigation of air pollutants. Involving policy-makers and relevant professionals such as medical professions during the research phase is also key to ensure that interventions evaluated by researchers will later on be promoted and adopted by public authorities. Likewise involving populations from the Global South and from overseas EU territories where HAP has both global environmental impacts and local health impacts is essential in a time of climate change.
