Exposure to ozone and metabolic syndrome: Korea National Health and Nutrition Examination Survey

Abstract Background Metabolic syndrome (MetS) is a major risk factor for cardiovascular diseases. Previous studies show inconsistent evidence on ozone's effect on MetS. This study aims to examine the association between long-term ozone exposure and MetS prevalence. Methods We utilized data from the Korea National Health and Nutrition Examination Survey (KNHANES, 2007-2022) linked with air pollution concentration data. Our study included adults aged 20 and over, and we calculated moving average ozone exposure for 1 to 24 months using the Community Multiscale Air Quality model. Multivariable logistic regression analysis was performed to estimate odds ratios (ORs) with 95% confidence intervals (CIs) for each 1 ppb increase in ozone exposure. Adjustment variables included sex, age, education level, income level, smoking history, alcohol consumption, physical activity, temperature, humidity, and region. Restricted cubic splines were used to assess non-linearity. We also divided exposure into quartiles and evaluated the OR comparing the lowest quartile to the others. All analyses incorporated sampling weights, stratification, and clustering to account for the complex survey design. Results The final analysis included 70,527 adults. MetS prevalence was 30.1%, higher in men (35.0%) than women (25.3%). Prevalence rose from 9.2% (20s) to 49.6% (≥70s). The average O3 concentration ranged from 27.4 to 27.9 ppb. One- and two-year ozone exposure were associated with ORs of 1.009 (95% CI: 1.005, 1.013) and 1.011 (95% CI: 1.007, 1.016), respectively. A non-linear association between ozone exposure and MetS was observed, with the ORs increasing in higher quartiles compared to the lowest quartile. Conclusions We used cross-sectional data from the 2007-2022 to investigate the association between long-term ozone exposure and MetS on a national scale. Our study found that increased long-term ozone exposure is associated with a higher MetS prevalence in adults. Key messages • Using KNHANES data from 2007–2022, we found a non-linear association between long-term ozone exposure and MetS, with higher ozone linked to increased prevalence. • Reducing ambient ozone levels should be prioritized as part of integrated public health strategies to prevent chronic metabolic diseases.