Particulate Exposure and Risk Factors for Respiratory Symptoms Among Tertiary Institution Students

Background: Ambient and indoor air quality have important health impacts and are primarily determined by the concentration of pollutants in the environment. Particulate matter (PM) is a mixture of solid and liquid particles suspended in the air and occurs in a variety of sizes, shapes, origins, and compositions. Understanding particulate matter levels and their health effects in microenvironments such as educational institutions is key for implementing targeted actions against exposure to this recognized environmental hazard. Objectives: This study aimed to assess the concentrations of particulates and examine the reported risk factors associated with respiratory symptoms among students in a higher institution, in Benin City, Nigeria. Methods: Indoor and outdoor particulate matter (PM2.5 and PM10) concentrations were measured for three months via a handheld portable air monitoring device. A cross-sectional survey was conducted using 330 modified respiratory symptom questionnaires (RSQs) to assess respiratory symptoms within the same period. Descriptive (mean, SD) and inferential (ANOVA, chi-square, logistic regression) analyses were performed using SPSS v22.0. Model fitness was confirmed (VIF = 1.12, HL test, p < 0.05), and adjusted odds ratios (aORs) were used to interpret associations. Results: The mean ranges of the PM2.5 and PM10 concentrations throughout the sampling sites were 43.7 ± 2.8 – 52.2 ± 5.0 µg/m3 and 56.6 ± 4.1 – 69.8 ± 6.9 µg/m3, respectively. The level of particulates was above the recommended WHO air quality guidelines at all the sampling locations. The calculated indoor and outdoor ratios were greater than 1 for the PM2.5 and less than 1 for the PM10 in most of the sampling sites. There was no clear association between increased concentrations of PM and respiratory symptoms, but a tendency to increase the risk of shortness of breath (adjusted odds ratios = 1.77; Cl = 1.042 – 3.021), wheezing (aOR = 1.56; Cl = 0.002 – 10.187) and chest tightness (aOR = 1.40; Cl = 0.001 – 84.446) among respondents. Gender (aOR = 2.12; Cl = 1.118 – 4.03) smoking status (aOR = 3.70; Cl = 1.19 – 6.91) and the presence of visible moulds in the classroom (aOR = 1.77; Cl = 1.042 – 3.021) were significant independent predictors of reported shortness of breath, wheezing and chest tightness among the respondents. Conclusion: The study found that the indoor and outdoor concentrations of particulates at all the sampling sites were higher than the prescribed WHO air quality standards, suggesting that the health of the exposed students is at risk. Although a positive association was found between elevated particulate matter concentrations and respiratory symptoms reported by respondents, this relationship was not statistically significant. The current study revealed that only sex, smoking status and the presence of visible moulds in classrooms were independent determining risk factors for reported respiratory symptoms among the students.