Introduction <p>Urban African adolescents suffer from undiagnosed and uncontrolled asthma symptoms. The purpose of this pilot study was to identify factors related to poorly controlled asthma symptoms and evaluate whether the objective measures suggested by the European Respiratory Society task force (ERS-TF) diagnostic algorithm for children assisted with asthma diagnosis.</p> Methods <p>Between July 2019 and November 2021, we conducted a cross-sectional cohort study of urban school-going adolescents between 12 and 14 years as part of the Achieving Control of Asthma in Children in Africa (ACACIA) project. The study comprised two stages; (a) screening for asthma symptoms and diagnosis and (b) asthma control test (ACT), pre and post-bronchodilator spirometry, and FeNO measurements in those who were screen-positive.</p> Results <p>Of 2093 adolescents screened, 180 were included, and 56% were female. Most participants had severe asthma symptoms (<i>n</i> = 128; 71%) and uncontrolled asthma (<i>n</i> = 157; 87%). Half (<i>n</i> = 90) had a previous asthma diagnosis, and were more likely to have uncontrolled asthma, <i>p</i> = 0.04. A significantly higher number of adolescents with uncontrolled asthma were exposed to traffic near their home (58% vs. 35%, p value &lt; 0.01). Those who were exposed to kerosene lamps and insect sprays were more likely to have airway inflammation; <i>p</i> = 0.02 and <i>p</i> = 0.01; respectively. The prevalence of abnormal spirometry and bronchodilator response (BDR) was 12%. By performing the BDR test in those with normal spirometry, we increased the diagnostic yield of the ERS-TF algorithm by 50%.</p> Conclusion <p>In this at-risk population, asthma symptoms are common, uncontrolled and related to environmental factors. In over half of those who undergo screening procedures such as spirometry, BDR and FeNO, the likelihood of a diagnosis remains low. Additional research involving non symptomatic control groups and longitudinal assessment is required to validate these results.</p>