A recent environmental survey released by Yale University and Columbia University shocked us by showing that Korea is one of the most polluted countries in the world.

The 2016 Environmental Performance Index places Korea near the bottom of the world in terms of air quality -- 173rd out of the 180 countries surveyed. Korea scored 45.51 out of 100.

The index evaluates how countries of the world protect ecosystems and human health from environmental harm based on 20 indicators, including air quality, health impact, climate and energy.

Specifically, Korea ranked 174th in average exposure to PM2.5 -- ultrafine particles less than 2.5 micrometers in diameter -- by scoring 33.46. China ranked bottom with a mere 2.26 points.

Korea took the lowest slot, along with Belgium and the Netherlands, in average exposure to nitrogen dioxide, a gas that principally comes from motor vehicle exhaust.

Korea scored zero points in this category, meaning that it has achieved little progress in reducing nitrogen dioxide in the atmosphere since 1997, the base year chosen for the biennial survey.

In 2011, nitrogen dioxide concentrations in Korea were 6.64 parts per billion, not much lower than 7.92 ppb in 1997.

Korea ranked low in other categories as well: 103rd in health impacts and 83rd in climate and energy. Korea’s overall EPI ranking in 2016 was 80th, a sharp drop from 43rd in 2014.

The downgrade is the result of Korea’s insufficient efforts to reduce carbon emissions and clean up its air.

In fact, Korea’s carbon dioxide emissions have been on the rise as a result of its increased reliance on coal-burning power plants to generate electricity.

Korea’s air quality has deteriorated in recent years due largely to an increase in diesel vehicles. According to the National Institute of Environmental Research, more than 40 percent of the fine particles in the Seoul area come from diesel vehicles.

Yet the government has been implementing the mistaken policy of treating diesel cars preferentially. As a result, the proportion of diesel vehicles in new car sales in Korea has risen from 10 percent to 45 percent over the past five years.

Government officials often blame China for air pollution in Korea. While China contributes significantly to worsening the problem, much of the fine dust is generated within Korea.

Last week, after weeks of dust-shrouded days, President Park Geun-hye told officials to prepare “special measures” to curb fine dust that poses a growing health threat to people.

The government needs to come up with a comprehensive package that includes, among other things, incentives to promote a shift toward clean fuels and low-carbon vehicles. Korea needs to advance its transition to new energy sources to resolve the air pollution problem.