South Korea’s air quality was ranked 173rd among 180 countries in a recent analysis, as the onslaught of fine dust particles continues to threaten public health every spring.

According to the 2016 Environmental Performance Index(EPI) on air quality, climate, energy and forestry resources unveiled on Monday by researchers at Yale University and Columbia University, South Korea scored 45-point-51 points out of 100 in the air quality section, putting it 173rd among 180 countries studied.

The EPI is a tally using statistics from some 20 items, including the environment, climate change, health, farming, fishing and maritime affairs, to measure sustainability per country. The index is announced every two years through the World Economic Forum.

South Korea also received 33-point-46 points in the category of Average Exposure to fine particulate matter(PM2.5), a measurement of how exposed citizens are to ultrafine air pollutants, putting it 174th among 180 countries. China scored the lowest, receiving two-point-26 points. 

South Korea was ranked at the lowest spot in Average Exposure to nitrogen dioxide(NO2), along with the Netherlands and Belgium.