The Trump administration’s aggressive regulatory rollback on the environment has rapidly led to worsening air quality in the U.S., according to a new study.

Researchers at Carnegie Mellon University said Tuesday that after seven years of a 24 percent decline in air pollution, it took just two years for the number of pollutants in the air to rise by 5.5 percent, from 2016 to 2018.

The study linked declining air quality to three factors, all tied to the climate crisis and the U.S. government’s refusal to reduce fossil fuel emissions that are warming the planet.

Since taking office in 2017, President Donald Trump has completed 10 regulatory rollbacks involving efforts to improve air quality and has slashed nine regulations on fossil fuel extraction industries.

Trump’s repeal of a rule requiring state authorities to track vehicle emissions on highways, his decision to change how oil and gas refineries monitor pollution, and his rollback of a rule limiting industrial pollution are among the decisions that have led to worsened air quality, according to the report written by Karen Clay and Nicholas Muller and published by the National Bureau of Economic Research.

“This is happening at a time when the EPA has disbanded its scientific panel reviewing fine particle air pollution,” tweeted Washington Post reporter Christopher Ingraham.