Atmosphere around Seogang Bridge next to Han River in Seoul is foggy with clouds of fine dust, Sept. 29. Yonhap

Yellow dust advisories were issued across Korea except for South Gyeongsang Province on Tuesday, with the fine dust level in Seoul hitting the highest point so far this year, authorities said.

The yellow dust advisories were upgraded from "attention" to "caution," the second highest in the environmental ministry's four-notch warning system, in Seoul, Incheon, Gyeonggi Province surrounding the capital and Gangwon Province as of early Tuesday afternoon, the environment authorities said.

All other remaining regions, except for South Gyeongsang, were under Level 1 yellow dust advisories.

A Level 2 advisory is issued when a fine dust alert, a warning when the hourly concentration of PM10 is higher than 300 micrograms per cubic meter for over two hours, is already in place due to yellow sand and there's a possibility of a big-scale yellow dust-related disaster.

Dust with a diameter of 10 micrometers or smaller, equal to PM10, can enter the lungs and lead to adverse health effects.

As of 1 p.m., the fine dust level remained "very bad" for the greater Seoul area and Gangwon, South Chungcheong and North Jeolla provinces, while the rest of the nation had "bad" fine dust levels.

In Seoul, the hourly average concentration of PM10 has reached 351 micrograms per cubic meter so far Tuesday, the highest point for this year.

The daily average concentration of PM10 stands at 260 micrograms per cubic meter for this year. (Yonhap)