Combined association of particulate matter and changes in physical activity on metabolic syndrome and profiles

Sedentary lifestyles and obesity increase the risk of metabolic syndrome (MetS). While physical activity (PA) is beneficial, particulate matter (PM) may worsen metabolic profiles. Given PA's outdoor nature, assessing its combined impact with air pollution is crucial. Currently, there is limited research directly comparing the potential harms of air pollution with the benefits of increased PA across various metabolic factors. This study uniquely examines changes in PA in conjunction with PM exposure to address this gap. A cohort study was conducted on 35,220 participants aged 40 or older examining changes in PA and PM exposure. PA was measured in metabolic equivalent tasks minutes per week (MET-min/week) using health examinations from 2010–2011 and 2012–2013. PA change was calculated by subtracting PA values from these observations. PM exposure was estimated using 4-year means. Adjusted odds ratios (aORs) were used to evaluate MetS risk for each PA change category. Increased PA generally reduced the risk of MetS and related factors, regardless of PM levels. In high PM groups, lower PA was associated with higher MetS risk (aOR 1.16, 95% CI 1.02–1.32, p-for-trend 0.004), while more PA lowered risk in low-to-moderate PM groups (aOR 0.87, 95% CI 0.80–0.96, p-for-trend < 0.001). Similar associations were observed for metabolic profiles, except for blood pressure. Greater PA change appears to be protective against MetS in both low-to-moderate and high PM exposure groups. Findings suggest that maintaining or increasing PA is beneficial for metabolic health, although individuals at hypertension risk should exercise caution.