Income and health outcomes in Sub-Saharan African countries: The role of environmental quality

Studies that extended analysis of the relationship between income, and role of environmental quality beyond the conditional mean-effect in panel studies are limited in ecological literature. This study extended analysis of the income-health relationship by accounting for slope distributional heterogeneity in 32 Sub-Saharan African countries (SSA), using data for the period 1996–2022. Life expectancy (LE) was utilised as a measure of health outcomes, while per capita income (PCI), and CO2 emissions served as measures of income and environmental quality respectively. Estimates of the conditional mean-effects was validated by two other estimators. Because variables deviate from expected normal distribution which renders the conditional mean-effect of limited policy relevance, a quantile regression was explored to examine the distribution of the direct-effect of income, and role of environmental quality across countries. Results of the conditional mean effect supports the idea that environmental quality significantly moderated the effect of income to determine health outcomes. This moderating influence arising from the interplay between PCI and CO2 emissions, further consolidates the direct-positive effect of income on health outcomes by 4.5 % which is relevant for countries that lie from the median to the upper level of longevity.