Sulfurous thermal waters as nature-based health resources: a public health and sustainability perspective.

The sustainability of healthcare systems has become a central public health concern as chronic diseases, rising therapeutic burden, and environmental constraints increasingly challenge service delivery models. While pharmacological treatments remain essential, complementary low-resource interventions may play a role in selected chronic conditions if framed within evidence-informed and policy-relevant care pathways. This article presents a Perspective on sulfurous balneotherapy as a potential component of sustainable models of care, using the Saturnia sulfurous thermal system as a paradigmatic and well-characterized example rather than an exceptional therapeutic resource. Drawing on concepts from public health policy, planetary health, and biological plausibility related to hydrogen sulfide exposure, the paper examines how such interventions might complement existing health services without substituting conventional medical treatments. The focus is on system-level considerations relevant to Universal Health Coverage, including therapeutic burden, patient acceptability, long-term feasibility, and integration into chronic care pathways in high-income health systems. Rather than providing a systematic review or reporting original experimental data, this Perspective aims to reframe sulfurous balneotherapy within contemporary debates on healthcare sustainability, clarify its limitations, and outline research and policy priorities needed to assess its role in equitable and resilient health systems.