Vietnam scored 33.4 points out of 100 in the biennial Environmental Performance Index compiled by scientists at American universities Yale and Columbia.

The report ranked 180 countries and territories around the world on 32 performance indicators across 11 categories covering environmental health and ecosystem vitality.

The categories are air quality, sanitation and drinking water, heavy metal, waste management, biodiversity, ecosystem services, fisheries, climate change, pollution emissions, agriculture, and water resources.

Vietnam’s low ranking resulted also from its struggles with climate change, according to the report.

It stood at 115th in air quality that measured household solid fuel use and PM2.5 average exposure.

PM2.5, super fine particles, measures a fraction of the width of a human hair, and is emitted by vehicles and industry. The World Health Organization Air Quality Guideline recommends an annual PM2.5 mean exposure threshold of 10 μg/m3 to minimize health risks.

According to the report, Vietnam’s air quality was worse than that of many other Southeast Asian countries like Brunei, Malaysia, Singapore and Thailand. In the Asia-Pacific region, it was in 18th place out of 25 economies.

In biodiversity and habitat, Vietnam placed at 150th due to failure to maximize the conservation potential of its protected areas, especially marine ecosystems.

It ranked 155th in climate change mitigation, which measured progress in combating global climate change, which exacerbates all other environmental threats and imperils human health and safety.

Vietnam, one of the highest emitters of greenhouse gases in Southeast Asia, seeks to cut greenhouse gas emissions by 8 percent between 2020 and 2030.

It was identified by the Intergovernmental Panel on Climate Change in 2014 as one of the countries likely to be most affected by climate change due to its extensive coastline, vast deltas and flood plains and location on the path of typhoons, and warned that 25 percent of its land mass might not be in use by 2100 due to sea level rise.

Rising temperatures and sea levels, and the increased frequency and intensity of extreme weather events combined with population growth and urbanization are increasing the risk of coastal erosion, urban flooding and drought.

Denmark topped the ranking with the world's cleanest air, followed by Luxembourg and Switzerland. The 10 most environmentally friendly countries in the world were European. The U.S. was 24th while China, which is plagued by worsening air pollution, was in 120th place.

Worsening air pollution in Hanoi and HCMC, Vietnam's two biggest metropolises, has become a major concern and repeatedly made headlines in 2019.

Officials have said the low quality of air in the cities is caused by construction, a growing number of cars and motorcycles, industries like steel works and cement factories, and coal-fired plants.

Research indicates the country suffers $10.8-13.2 billion worth of economic losses associated with ambient air pollution each year, equivalent to about 5 percent of its GDP.