Published in PLOS One on 2026-04-28, this study is presented as an attributed evidence briefing. The excerpts below are the original researchers’ words, reproduced under their Creative Commons Attribution licence. Health Signal has selected the abstract and, where needed, opening background paragraphs; the complete methods, results, limitations and references remain in the linked paper.
Original authors: Funmito Omolola Fehintola, Adesola Olumide, Adesegun Fatusi, Olayemi Omotade
Source: PLOS One • DOI 10.1371/journal.pone.0347739
Read the complete primary study ↗ · Creative Commons Attribution licence
From the researchers
Abstract
Smoking is one of the modifiable risk factors of non-communicable diseases and cause of premature death. Surveillance is most often based on self-reported data among adolescents, but few studies have measured exhale breath using Carbon Monoxide in them. This study aimed to measure the prevalence of smoking by measuring exhaled Breath Carbon Monoxide Threshold Levels and Self-Reported Cigarette Smoking in a sample of in-school adolescents in Osun State Nigeria.
The study employed a descriptive, cross sectional study design, a multi-stage sampling technique was used to select 616 adolescents from selected secondary schools in Osun State. Smoking status of adolescents were measured using Smokerlyzer, and WHO STEPwise questionnaire. The Cut-off point for current smokers using the exhale level of carbon monoxide (eBco) was ≥ 10parts per million. The collected data were entered into SPSS version 20 software for statistical analysis. Multivariable logistic regression analyses were done to identify the true effect of predictor variables on the outcome variable. Statistical significance was declared at a p-value < 0.05.
Smoking by self- report was 80 (13.0%) while the smokerlyzer detected 168 (27.3%) current smokers. Cohen’s κ = 0.063 (smokerlyzer) showed poor agreement between self-report and objective measures. Determinants of smoking include older age (AOR = 1.59, CI = 1.01–2.34), class level, compared with students in JSS1, SSS1 (AOR = 0.14, 95% CI: 0.07–0.26), and SSS2 (AOR = 0.46, 95% CI: 0.23–0.78) were significantly less likely to smoke. Rank regression analysis revealed that age was negatively associated with the rank of smoking status (B = −0.10, p = 0.008).
Prevalence of smoking using smokerlyzer was higher compared to self-report among in-school adolescents. The study identified older age and class as important predictors of smoking Targeted health education should be done in schools to enhance smoking cessation.
Introduction
Smoking is a major public health concern, resulting into to numerous health problems and complications worldwide. Globally, approximately 1.3 billion people use tobacco, making it one of the leading causes of preventable diseases [1]. Around 80% of the 1.3 billion tobacco users worldwide live in low- and middle-income countries, where the burden of tobacco-related illness and death is heaviest [2].The economic costs of tobacco use are substantial and include significant health care costs for treating the diseases caused by tobacco use as well as the lost human capital that results from tobacco-attributable morbidity and mortality [1].
Nigeria, the most populous country in Africa, has 22% of its population to be adolescents and has one of the leading tobacco markets in Africa, with over 18 billion cigarettes sold annually [3]. Adolescents in Nigeria are particularly vulnerable. Every year, more than 16,100 of Nigeria’s population die from tobacco-caused disease; 748,800 Nigerians aged 15 years or older and more than 25,000 aged 10–14 years use tobacco every day [4]. Nigeria signed the WHO FCTC in 2004, ratified it in 2005, and domesticated it through the National Tobacco Control Act of 2015 [5,6].
Reading this evidence
Use the full paper to check the study design, participant selection, comparator and outcome definitions before drawing a practical conclusion. An association does not by itself show cause and effect. A reported performance measure needs its denominator and uncertainty. A finding from a particular facility, sample or time period should retain that scope when it is discussed elsewhere.
This briefing makes the source accessible within the wider public health desk. It does not assess an individual patient or certify a product. When considering relevance to another health system, examine the original authors’ account of context and limitations, then seek local implementation evidence. The related reporting below provides other studies to read alongside this one; it is a topic connection, rather than a claim that their results are directly comparable.
© 2026 Funmito Omolola Fehintola, Adesola Olumide, Adesegun Fatusi, Olayemi Omotade. Excerpts reproduced under CC BY. Selection, formatting and contextual notes by Health Signal. The researchers are the authors of the source study, not members of Health Signal’s staff.
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