The number of days with ultra fine dust density levels considered “bad” hit a record low last year.

According to the environment ministry on Monday, the annual tally of 17 days registering 36 micrograms per cubic meter or higher was six days fewer than in 2021, and the lowest since the ministry began compiling related data in 2015.

The ministry also reported that there were no "very bad" days of ultra fine dust levels exceeding 76 micrograms per cubic meter in 2022.

The annual average density of ultra fine dust in 2022 was a record low of 18 micrograms per cubic meter, the same as the previous year, which was a 31-percent drop from 26 micrograms per cubic meter in 2015.

The ministry cited the continued decline of ultra fine dust from China, increased precipitation last year in Seoul and other central areas, reduced days of yellow dust and atmospheric stagnation as well as the government's fine dust management measures.