Background: The prevalence of metabolic syndrome (MetS) has increased rapidly, with considerable variation between European countries. The study examined the relationship between air pollutants, greenspace and MetS and its components in Czech and Swiss populations. Methods: Cross-sectional data from the Czech HAPIEE (n=4,931) and the Swiss SAPALDIA (n=4,422) cohorts included participants aged 44-73 years. MetS was defined as abdominal obesity plus two additional components (hypertension, diabetes, low HDL cholesterol, elevated triglycerides). Annual mean concentrations of PM10, PM2.5, NO2 and greenspace (defined as annual mean of NDVI within 500 m) were assigned to the individual residential level. We estimated odds ratios (OR) using multivariable logistic regressions with cluster-robust standard error, controlling for multiple confounders. Results: The prevalence of MetS was significantly higher in Czech (51.1%) compared to Swiss (35.8%) population as were the concentration means of PM10 and PM2.5. In HAPIEE, 5 μg/m3 increase in PM2.5 was associated with 14% higher odds of MetS (OR=1.14; 95% CI 1.01-1.28). In SAPALDIA, no evidence was found for the associations between air pollutants and MetS (e.g. OR=1.01; 95% CI 0.90-1.13 for PM2.5). No protective effects of NDVI on MetS were observed. Upon inspection of MetS components, PM2.5 and PM10 exposures were associated with higher odds of hypertension and elevated TG in HAPIEE only, while PM2.5, PM10 and NO2 were associated with higher odds of diabetes in SAPALDIA only. Conclusion: Individuals with higher exposures to PM2.5 may be at higher risk of MetS. The differential associations with MetS components between the cohorts deserve further investigation.