An ultrafine dust advisory is in effect for Seoul.
 
The Seoul metropolitan government said that it issued the advisory as the average concentration level of ultrafine dust surpassed 65 micrograms per cubic meter as of 10 a.m. Thursday.
 
In particular, the average concentration reached 79 micrograms per cubic meter in Yangcheon District in southwestern Seoul.
 
The city government attributed the attack of ultrafine dust to highly concentrated air pollutants from China, atmospheric stagnation and fine dust piled up over the Korean Peninsula.
 
This is the sixth ultrafine dust advisory issued this year.
 
The city government advises people to wear masks while outdoors and asks children, seniors and those with respiratory illnesses to stay inside.