Johns Hopkins University researchers find that the world is not on track to reach a new low in air pollution

The world’s air pollution has dropped to its lowest level in nearly 50 years, according to a new report from Johns Hopkins University.

Researchers from the university’s Department of Environmental Science and Engineering published their findings Monday in the journal Science.

The researchers found that a reduction of 5.4 percent of air pollution over the past decade had been achieved.

The world has reduced its annual average levels of ozone and particulate matter, or PM 2.5, from 4.8 to 3.9 micrograms per cubic meter.

The decrease in PM 2, or particles smaller than 2.25 microns, is the second-lowest level ever recorded, and is the lowest level ever achieved for a single year, after the U.S. had reached a record level in 2016.

The new report, based on data from around the world, also found that more than half of all emissions are now being reduced by more than 30 percent, with China taking the lead with about half of the reductions.

“There’s been a huge reduction in emissions of greenhouse gases that we’ve seen since 2000,” said James Friese, the study’s lead author and a professor of atmospheric sciences and climate change at Johns Hopkins.

“It’s not just in China, it’s not even just the U and China.”

The researchers said they would continue to monitor trends to see whether there is a continuing trend toward further reduction, but said that so far the world has remained on track for a reduction.

They said they found that emissions were increasing in Europe, particularly in the Netherlands, the UK and France, where the increase is greater.

They also said that air pollution in parts of China, which is experiencing severe weather and economic challenges, is increasing.

“We don’t have the full picture yet,” Frieses said.

The report came as U.K. Prime Minister Theresa May announced her government will slash the nation’s CO2 emissions by 20 percent in 2020, from a planned 40 percent.