A recent UN agency report says that levels of key air pollutants temporarily plunged by unprecedented levels during COVID-19 lockdowns and travel restrictions last year.

The World Meteorological Organization(WMO) made the assessment in its inaugural Air Quality and Climate Bulletin which was published on Friday. 

The agency noted that ultrafine dust particles (PM 2.5) fell by up to 40 percent across Africa, South America and Southern Asia and by smaller amounts in parts of Europe and North America.

It said that lockdowns and travel restrictions led to a “dramatic short-lived fall in emissions” of key air pollutants, especially in urban areas.

The bulletin, which compared 2020 air quality with readings from previous years, showed that levels of harmful nitrogen dioxide emitted from the burning of fuel fell nearly everywhere across the world and by as much as 70 percent.

The study analyzed air quality changes involving pollutants such as sulfur dioxide, nitrogen oxides, carbon monoxide and ozone.

The organization, however, cautioned that reductions in pollution last year were short-lived and patchy and some pollutants continued to emerge at concerning levels.

The WMO's Secretary-General Petteri Taalas said that a pandemic is not a substitute for sustained and systematic action to tackle climate change and safeguard the health of people and the planet.

The report was published ahead of the International Day of Clean Air for Blue Skies observed on September 7. The idea was proposed by President Moon Jae-in at the UN Climate Action Summit in 2019.