TITLE:
School Indoor Air Pollution Sources and Their Association with Respiratory Symptoms among Secondary School Students Aged 10 to 17 Years in Buea, Cameroon: A Cross-Sectional Study
AUTHORS:
Lifafa Kinge Kange, Kaharu Sumino, Sean Semple, Alison Gene Lee, Babatunde Awokola, Ghangha Jamin Ghangha, Kum Mineva Ziagha, Asanga Ngu Winston, Cheghe Perez Kebei, Vamtowe Hezal Tracy, Nupa Kawo Christelle
KEYWORDS:
Indoor Air Quality, Particulate Matter, Carbon Monoxide, Respiratory Symptoms, Secondary Schools, Cameroon, Adolescents
JOURNAL NAME:
Open Journal of Epidemiology,
Vol.16 No.4,
October
8,
2026
ABSTRACT: Background: Indoor air quality in schools is a public health concern that has received limited attention in sub-Saharan Africa. Children spend a substantial proportion of their time in classrooms and are physiologically more vulnerable to airborne pollutants than adults. No studies had previously characterized classroom air quality or its respiratory health effects in secondary schools in Cameroon. Objectives: This study assessed sources of indoor air pollutants, including fine particulate matter (PM2.5), carbon monoxide (CO), humidity and temperature, and determined their association with respiratory symptoms among students aged 10 to 17 years in secondary schools in Buea, Cameroon. Methods: A school-based cross-sectional study was conducted across ten secondary schools. A total of 1674 students were enrolled through consecutive and stratified random sampling. Sources of indoor air pollution such as PM2.5, CO, temperature, and humidity were assessed using a validated WHO checklist comprising exposure indicators. CO levels were continuously monitored in six schools using Lascar EL-USB-CO data loggers. Respiratory symptoms were measured using the validated AstraZeneca Respiratory Symptom Questionnaire. Logistic regression was used to identify independent risk factors of respiratory symptoms. Results: All ten schools demonstrated high to very high PM2.5 checklist exposure (78.6% very high risk; 21.4% high risk), primarily driven by universal use of chalk and blackboards, dust accumulation, and absence of air filtration. Out of the 1674 participants, 46.8% (784) had a moderate risk exposure level to Humidity and temperature, 27.6% (462) had low risk, 17.4% (291) had High Risk, and 8.2% (137) had very high risk. One school recorded a mean CO level of 20.50 ppm, exceeding the WHO/EPA acceptable ceiling of 5 ppm. A total of 27.0% of students reported respiratory symptoms; of these, 73.0% were mild, 20.2% moderate, 5.8% severe, and 1.0% very severe. In multivariate logistic regression, significant independent predictors of respiratory symptoms included a prior diagnosis of respiratory disease (aOR 3.24, 95% CI 1.40 - 7.53; p = 0.006), presence of allergies (aOR 1.66, 95% CI 1.25 - 2.21; p Conclusions: From this study, it was realized that secondary school students assessed by checklist exposure indicators to sources of indoor air pollution are exposed to PM2.5, temperature, and humidity ranging from moderate to very high-risk levels. Abnormal CO measurement was captured in 1 of the schools. Respiratory symptoms were associated with the level of exposure to temperature and humidity. Policy action to improve classroom air quality, replace chalk-based teaching tools, and systematically monitor indoor pollutants in Cameroonian schools is warranted.