Monitoring of PM2.5 Using Well-Calibrated Low-Cost Sensors over One Year in Burkina Faso

Abstract

Air pollution causes more than 8.34 million premature deaths worldwide. Most of these deaths occur in the Global South, particularly in Africa. However, the means of observing this air pollution in these countries are lacking. Knowledge of pollutant concentration levels and their distribution in time and space is inadequate or nonexistent in most African countries. This study focuses on the temporal and spatial distribution of PM_2.5 in Burkina Faso, a country of more than 22 million residents yet with very scarce air pollution literature. The study used Clarity low-cost sensors. The sensors were placed at 19 sites throughout the country, including 13 in Ouagadougou, the capital, and three in Bobo-Dioulasso and three in Koudougou, the second and third largest cities in Burkina Faso, respectively. The measurements were taken over a one year period (November 2021 to November 2022). The data was corrected using a Gaussian Mixture Regression trained on a 2-month colocation of a TEOM with a Clarity monitor in Ouagadougou. The corrected mean daily concentrations measured at all of the sites ranged from 17 to 68 μg/m³, with an overall daily average of 46.7 μg/m³. The city averages are 48.5 μg/m³ for Ouagadougou, 46.9 μg/m³ for Bobo-Dioulasso, and 38.7 μg/m³ for Koudougou. These concentrations are significantly higher than the World Health Organization’s recommended safe daily guideline, 15 μg/m³. Measurement values are highest during the dry season, which is dominated by the Harmattan winds from the Sahara desert. At all sites, between 61% and 87% of the measured days exceeded the WHO daily guidelines for PM_2.5. These measurements show the need to undertake an action plan to reduce air pollution in general in Burkina Faso in order to better protect the population health.