FACIAL AND NASAL ANATOMICAL STRUCTURES AND THEIR ROLE IN AIR POLLUTION–RELATED RESPIRATORY MORBIDITY IN NIGERIAN CITIES

Abstract

This cross-sectional study examined the relationship between facial and nasal anatomical structures and air pollution–related respiratory morbidity across six major Nigerian cities representing each geopolitical zone: Lagos, Port Harcourt, Enugu, Abuja, Kano, and Maiduguri. A total of 1,200 adults aged 18–65 years with at least five years of residence were recruited through multi-stage sampling. Air pollution exposure was assessed using fixed-site monitors and seven-day personal sensors for PM2.5, PM10, NO₂, SO₂, and CO, integrated with GIS mapping. Facial and nasal anatomy was evaluated using 3D facial scans, low-dose CT imaging, and rhinomanometry, while respiratory health was assessed via spirometry, ATS questionnaires, and medical record review. Analyses included descriptive statistics, bivariate correlations, multivariate regression, GIS mapping, and computational fluid dynamics (CFD) simulations. Findings revealed that wider nasal cavities and larger cross-sectional areas reduced susceptibility to asthma, chronic bronchitis, and allergic rhinitis, whereas narrower passages and higher airflow resistance increased vulnerability. Northern cities exhibited nasal structures adapted to dusty, arid environments, while southern cities had narrower nasal cavities and higher respiratory morbidity despite effective deposition of coarse particles. CFD simulations confirmed that nasal morphology influenced airflow patterns and particulate deposition, supporting anatomical modulation of individual exposure risk. These results highlight the interaction between environmental and biological factors in determining respiratory health. Public health strategies should integrate air pollution control, targeted respiratory screening, and personalized interventions considering anatomical differences. Understanding how nasal and facial structures influence pollutant deposition can improve risk assessment and guide mitigation efforts in urban populations exposed to high levels of air pollution.