Measuring ambient particulate matter in three cities in Cameroon, Africa

•PM1.0 particle count is monitored for the first time in Central Africa.•PM2.5 and PM10 mass concentrations are elevated in Cameroon.•Carbonaceous and non-carbonaceous PM contribute to PM2.5 in Cameroon.•Trash burning and cooking exhaust elevate PM concentrations in city outskirts.

This is the first study of particulate matter (PM) air pollution in Cameroon. In this study, mass concentration and PM size fractions as well as carbonaceous contribution to PM are measured in Bafoussam, Bamenda, and Yaoundé, Cameroon. Average concentrations in Bafoussam, Bamenda, and Yaoundé of PM2.5 are 67 ± 14, 132 ± 64, and 49 ± 12 μg/m3 and PM10 are 105 ± 29, 141 ± 107, and 65 ± 21 μg/m3, respectively. Daytime levels of PM2.5 and PM10 are seen to be higher than nighttime levels in all cities except Bamenda where nighttime levels are higher for both PM sizes. In Bafoussam, the average PM1.0 particle number concentration during the day is 19,800 pt/cc and during the evening is 15,200 pt/cc. PM2.5/PM10 mass ratios are 0.65 ± 0.05, 0.75 ± 0.05, and 0.78 ± 0.09 for Bafoussam, Bamenda, and Yaounde, respectively. Elemental carbon (EC) and organic carbon (OC) contribution to PM2.5 in Bafoussam, Bamenda, and Yaoundé are 3.9%, 2.9% and 12% for EC and 17.7%, 23.6%, and 34.2% for OC, respectively. After conducting spatial variability of PM mass concentration and size fractionation sampling at various locations within each of the three cities, we find that PM2.5 averages are highest during commercial meal preparation in Bafoussam (684 ± 546 μg/m3), and on the road in Bamenda (417 ± 113 μg/m3) and Yaoundé (110 ± 57 μg/m3). Additional air quality research in Central and West Africa is necessary to begin implementing policy steps that influence change and to advocate for improved health conditions in this rapidly expanding region of the world.

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