SEOUL — CNBC reports Seoul officials waived public transportation fees during commuter hours as the daily average density of ultra-fine dust remained above 50 micrograms per cubic meter — a level that's widely considered harmful.

Authorities also limited car use for public employees, closed 360 parking lots, and reduced construction work on government-funded projects. The policies were first introduced last year when Seoul's air quality index exceeded 179 micrograms per cubic meter of fine dust, the highest level among global metropolitan cities after New Delhi in India.

Asia's fourth-largest economy is the eighth-worst performing country in Verisk Maplecroft's 2018 Air Quality Index. India and Bangladesh took first and second place, respectively. For the full story, click here.