Exploration of the Spatial and Temporal Patterns of Surface Ozone Concentrations for Development of Ozone Prediction Model in South Korea

As ozone concentration has consistently increased over time and toxicological studies suggested possible impacts on human health, recent epidemiological studies focused on the impact of long-term exposure to ozone on cardiovascular and respiratory diseases. However, there have been few studies in South Korea. With the goal of providing practical guidance to developing ozone prediction model for future epidemiological studies in South Korea, the present study aimed to explore temporal and spatial patterns of ozone concentration using regulatory monitoring data collected over 19 years. Given hourly measurements at 135 similar to 388 sites during 2001 similar to 2019, we computed daily 8-hour maximum and averaged over the warm season from May to September as the daily- and annual-representative concentrations. Using hourly, daily, monthly, and annual ozone concentrations, we explored short-term and long-term temporal patterns. In addition, we investigated spatial patterns using summary statistics of annual concentrations across 16 Metropolitan Cities and Provinces and spatial correlation structure over the country. Furthermore, we compared the temporal and spatial patterns of ozone with those of weather conditions as well as VOCs and NOx emissions. Over the past 19 years, annual ozone concentrations have increased by about 13 ppbv (42%) with a consistently increasing trend and showed the highest between May and June. In the spatial pattern, ozone concentration was lower in urban areas than in rural areas. The temporal pattern of ozone was similar to those of solar radiation, while NOx and VOCs generally showed negative correlation with ozone over space and time. Our findings provided temporal and spatial characteristics of ozone which can help future exposure assessment for epidemiological studies in South Korea.