The entire country was on alert on Thursday as toxic haze from China was blown into the Korean Peninsula.
The National Institute of Environmental Research said that the concentration of fine particles would stay at the mildly dangerous level of 81-120 ㎍/㎥ on average across the country from Thursday until Friday morning and advised old or weak people and patients with respiratory diseases to avoid staying outdoors.
The Seoul Metropolitan Government also issued a preliminary warning on Thursday afternoon. It said the haze was blown in on westerly winds, blanketing Baeknyeong Island, the westernmost island, and then Seoul.
In Beijing at 2 p.m. Thursday, the concentration of ultrafine particles had reached 482 ㎍/㎥, more than 9.6 times Korea's safe standard of 50 ㎍/㎥ and 19.3 times the World Health Organization standard of 25 ㎍/㎥, according to the Seoul city government. Concentration of fine particles in Beijing has also reached the level of 600~700 ㎍/㎥.
Ultrafine dust particles are far smaller and more harmful to the health than fine particles as they cannot be filtered by the respiratory tract but stick to directly to the alveoli.
Experts believe the haze will continue until the weekend. "China is so thick with haze that winds are bound to carry more to Korea," said Chung Yong-seung of the Korea Centre for Atmospheric Environment Research. "It's likely that we'll have a heavier concentration of fine particles on Saturday than on Thursday."
But the National Institute of Environmental Research said winds will likely change directions on Friday afternoon.