Environmental Policy Stringency, Air Quality, and Human Health in the Context of Sustainable Development: Evidence from Europe and Africa

Air pollution remains a major global environmental and public health challenge, with fine particulate matter (PM2.5) contributing substantially to premature mortality. Environmental policy stringency is increasingly used to reduce emissions and population exposure, yet its effectiveness varies across institutional and economic contexts. This study examines the relationship between environmental policy stringency and PM2.5 exposure, and its implications for human health, through a comparative analysis of Germany and France in Europe and South Africa and Kenya in Africa. Results reveal marked regional disparities. Germany and France exhibit high policy stringency scores of approximately 5.5 and 5.1, respectively, alongside PM2.5 exposure levels of around 10 µg/m3 in 2020. In contrast, South Africa and Kenya experience exposure levels near 24 µg/m3, more than twice those observed in the European countries. Germany also reduced PM2.5 exposure by more than 15% between 2010 and 2020, coinciding with stronger environmental regulation, renewable energy investment, and effective enforcement. Overall, stringent environmental policies are associated with improved air quality and reduced population exposure, but their effectiveness depends on governance quality, institutional capacity, energy-system characteristics, and regulatory enforcement. The findings emphasize context-sensitive environmental governance, stronger institutional capacity, effective regulatory implementation, and clean-energy transitions to improve air quality and public health.