Non-Linear evidence from generalised additive models across national environmental health

Objective Greenhouse gas emissions are a phenomenon that has a significant impact on the environment and can pose a threat to various aspects of life if not curtailed or given adequate attention. The extent of these emissions differs by region, but the consequences are undeniable. This study aims to determine the effects and relationships of these emissions on economic and health factors. Methods Using Generalised Additive Models (GAMs), this study investigates the relationships among environmental stresses, economic growth, and health consequences. The analysis considers per capita emissions from gas, liquid, and solid fuels, together with economic indicators like GDP per capita and health expenditure, as well as health outcomes like mortality rates (death rates, DR) and disease prevalence, using data from 40 industrialised and developing nations. Results The results show significant heterogeneity among income groups; they also partially corroborate the Environmental Kuznets Curve (EKC) theory. Greenhouse gas emissions are strongly correlated with economic growth, despite their connection to increased mortality. The health implications of solid fuels are the most severe, especially concerning chronic diseases and infant mortality, whereas the results for liquid fuels are more inconsistent and unpredictable. The quality of institutions and healthcare systems is an important variable, and a classification of countries based on their GAM profiles reveals that traditional development categories frequently fall short. Conclusion This study demonstrates how crucial GAM modelling is for representing intricate, non-linear connections in environmental and health economics. Instead of using a single-variable approach that limits the analysis, a two-variable method is applied when the important factors affecting the results (GDP and DR) are clearly identified. These results demonstrate that economic expansion by itself does not ensure improved environmental or health outcomes. Proactive and situation-specific policies are still crucial, which in turn influences the form of the recommendations to address the negative effects. Furthermore, considering different geographic areas provides a broad perspective on the differences in their dynamics, establishing a framework for national and international collaborations that can leverage the expertise and experience of countries that have curtailed their effects to a reasonable level.