On the 20th at noon, the Seoul Health and Environment Research Institute issued the first fine dust (PM2.5) advisory of the year. A fine dust advisory is issued when the hourly average concentration exceeds 75 micrograms per cubic meter for more than two hours. The research institute noted, "It is estimated that the concentration of fine dust has increased due to the accumulation of domestic air pollutants, combined with the inflow of foreign pollutants into the metropolitan area."
Fine dust can enter the lungs and blood vessels when a person breathes, potentially harming health. Health authorities recommend that citizens, including those with respiratory or cardiovascular diseases, the elderly, and children, refrain from going outside. If it is unavoidable to go out, wearing a health mask is advisable.