Source apportioned air pollution monitoring for Nairobi

The air pollution levels in Nairobi structurally exceed the WHO limit values, posing a substantial health risk to the city’s residents. In 2022, Nairobi City County (NCC)adopted the Nairobi City County Air Quality Act, a legal framework for comprehensive air quality management that is operationalized by the Nairobi City County Air Quality Action Plan (2025-2029). To fulfil this obligation, action perspective is required that is based on detailed insight into the origin of pollution. NCC and TNO have teamed up to monitor the air quality in the city using a source apportioned modelling approach. This presentation shows the results of a first demonstration over Nairobi that has been made by NCC and TNO.

Source apportionment simulations provide insight into the source specific contributions to air pollution and the geographical origin of the pollution. Using a local emission inventory, labelled runs with TNO’s chemical transport model LOTOS-EUROS are set up. The priority emission sources, such as transport, waste management, construction, and industry, as well as the geographical origin (the different counties in and around Nairobi) are labelled.