Spatiotemporal Relationship between Air Pollution and Upper Respiratory Tract Infection Cases Among Children Under Five: A Case Study of Nakuru County, Kenya (2020-2022)

Air pollution seriously threatens respiratory health, particularly for children under five. The majority of air pollution-related fatalities occur in low- and middle-income countries, with Africa bearing a significant burden. The rapid urbanization, vehicle emissions, and inadequate waste management in Kenya have led to a surge in respiratory illnesses, such as Upper Respiratory Tract Infections (URTI) in Nakuru County. To address this pressing issue, this study explored the use of remote sensing data to analyze pollutant levels (CO, NO2, SO2, and PM2.5-AOD) and URTI cases from 2020 to 2022. This research aimed to uncover the correlation between air pollution levels and respiratory health outcomes, emphasizing the urgent need for action. Health facility data from KHIS and WHO were mapped using ArcGIS, with a 10 km buffer for spatial analysis. Google Earth Engine extracted and processed pollutant data (CO, NO2, SO2, PM2.5). Statistical analysis was conducted using Pearson, Spearman, and Mann-Kendall tests in R to analyze the correlation between pollutants and URTI cases, providing insights into temporal trends and spatial distributions of contaminants relative to health outcomes. The spatial analysis showed low and moderately distributed CO concentrations, consistent levels of PM2.5-AOD, and a peak in URTI cases from May 2021 to February 2022, with no clear evident seasonal correlation with NO2 levels. SO2 levels remained low, and CO variations showed no seasonal association with URTI. AOD was lower in early 2020, 2021, and January 2022 without affecting the URTI patterns. The correlation analysis revealed weak positive relationships between URTI and pollutant levels, with Pearson coefficients of 0.042 and 0.002, respectively, and even weaker relationships for PM2.5-AOD. This suggests that other unmeasured factors might influence URTI incidences or that the analysis needed to capture the impact of pollutants fully. However, these findings are crucial as they highlight the need for further exploration of indoor air pollution, socioeconomic status, nutrition, and genetic predisposition to gain a comprehensive understanding of this issue. They have the potential to significantly impact future research and policy decisions in this area.