Burden of Secondhand Smoke and Its Links to Chronic and Metabolic Conditions: WHO STEPS 2021

Abstract

Secondhand smoke (SHS) remains a preventable exposure with substantial cardiometabolic implications. Using the WHO STEPS conceptual framework as the organizing scaffold, this review summarizes 2021 survey patterns for SHS prevalence alongside associations with chronic respiratory disease, hypertension, dyslipidemia, and impaired fasting glucose. Population-based analyses consistently demonstrate dose-response relationships between household or workplace SHS exposure and adverse metabolic profiles, including higher triglycerides and reduced HDL-cholesterol. Mechanistic pathways span particulate-induced oxidative stress, endothelial dysfunction, and inflammatory cytokine activation that disturb insulin signaling. Policy interventions—comprehensive smoke-free legislation, taxation, and cessation support—show measurable downstream reductions in hospitalizations for ischemic heart disease and asthma; however, evidence for metabolic endpoints is emerging and warrants longitudinal confirmation. We outline priorities for future STEPS rounds: cotinine-validated exposure, standardized metabolic phenotyping, and equity-focused analyses for women and informal-sector workers who bear disproportionate SHS burdens.