The Effects of Short-Term and Very Short-Term Particulate Matter Exposure on Asthma-Related Hospital Visits: National Health Insurance Data.

PURPOSE: The purpose of this study was to investigate the effects of short-term and very short-term exposure to particulate matter (PM) exceeding the daily average environmental standards for Korea (≤100 µg/m³ for PM10 and ≤50 µg/m³ for PM2.5) on on asthma-related hospital visits. MATERIALS AND METHODS: This was a population-based, case-crossover study using National Health Insurance and air pollution data between January 1, 2014 and December 31, 2016. The event day was defined as a day when PM exceeded the daily average environmental standard (short-term exposure) or daily average environmental standard for 2 hours (very short-term exposure). The control day was defined as the same day of the week at 1 week prior to the event day. RESULTS: Compared with control days, asthma-related hospital visits on the 24-hr event days and 2-hr event days increased by 4.10% and 3.45% for PM10 and 5.66% and 3.74% for PM2.5, respectively. Asthma-related hospital visits increased from the 24-hr event day for PM10 to 4 days after the event day, peaking on the third day after the event day (1.26, 95% confidence interval, 1.22-1.30). Hospitalizations also increased on the third day after the event. While there was a difference in magnitude, PM2.5 exposure showed similar trends to PM10 exposure. CONCLUSION: We found a significant association between short-term and very short-term PM exposure exceeding the current daily average environmental standards of Korea and asthma-related hospital visits. These results are expected to aid in establishing appropriate environmental standards and relevant policies for PM.