Air quality assessment in three East African cities using calibrated low-cost sensors with a focus on road-based hotspots

Research output: Contribution to journalArticlepeer-review

Authors

  • David Ng'ang'a
  • Michael Gatari
  • Abel W. Kidane
  • Zinabu Alemu
  • Ndawula Derrick
  • Mbujje J. Webster
  • William R. Avis

Abstract

Poor air quality is a development challenge. Urbanization and industrial development along with increased populations have brought clear socio-economic benefits to Low-and Middle-Income Countries (LMICs) but can also bring disadvantages such as decreasing air quality. A lack of reliable air quality data in East African cities makes it difficult to understand air pollution exposure and to predict future air quality trends. This work documents urban air quality and air pollution exposure in the capital cities of Kampala (Uganda), Addis Ababa (Ethiopia) and Nairobi (Kenya). We build a situational awareness of air pollution through repeated static and dynamic mobile monitoring in a range of urban locations, including urban background, roadside (pavement and building), rural background, and bus station sites, alongside vehicle-based measurements including buses and motorcycle taxis. Data suggest that the measured particulate matter mass concentrations (PM 2.5, PM 10) in all studied cities was at high concentrations, and often hazardous to human health, as defined by WHO air quality guidelines. Overall, the poorest air quality was observed in Kampala, where mean daily PM 2.5 and PM 10 0.84). This link between roadside emissions and indoor air pollution within buildings located close to the road should be explored more fully. This study, through a series of case studies, provides clear evidence that roads and traffic need to be a focus for mitigation strategies to reduce air pollution exposure in East African cities. = concentrations were significantly above the WHO limits at urban background locations by 122% and 69% and at roadside locations by 193% and 215%, respectively. Trafficis clearly a major contributor to East African urban air pollution; monitoring in Kampala and Addis Ababa, on motorcycle taxis, in buses and at bus stations indicated that drivers and commuters were exposed to poor air quality throughout their commute. Road-related air pollution can also impact indoor locations near roads. Using one exemplar building located within Nairobi’s Central Business District, it is shown that measured outdoor PM concentrations significantly correlate with the indoor air quality (r = 0.84). This link between roadside emissions and indoor air pollution within buildings located close to the road should be explored more fully. This study, through a series of case studies, provides clear evidence that roads and traffic need to be a focus for mitigation strategies to reduce air pollution exposure in East African cities.

Bibliographic note

Funding Information: The work is funded by the UK Department for International Development (DFID) via the East Africa Research Fund (EARF) grant ‘A Systems Approach to Air Pollution (ASAP) East Africa’ and EPSRC (EP/T030100/1). Publisher Copyright: © 2021 The Author(s). Published by IOP Publishing Ltd.

Details

Original languageEnglish
Article number075007
JournalEnvironmental Research Communications
Volume3
Issue number7
Publication statusPublished - 23 Jul 2021

Keywords

  • Paper, Atmospheric science, air quality, particulate matter, transport, low-cost sensors, nairobi, kampala, addis ababa