Seouryeok, Seoul PM2.5 (fine particulate matter) AQI is 50 - Seouryeok, Seoul PM10 (respirable particulate matter) AQI is 35 - Seouryeok, Seoul NO2 (nitrogen dioxide) AQI is 25 - Seouryeok, Seoul SO2 (sulfur dioxide) AQI is 6 - Seouryeok, Seoul O3 (ozone) AQI is 15 - Seouryeok, Seoul CO (carbon monoxide) AQI is 5 -