Hawaii’s major industrial facilities reduced the amount of harmful chemicals released into the environment by 4% in 2018, the U.S. Environmental Protection Agency reported in its annual Toxic Release Inventory.

The inventory tracks how industrial facilities like factories, mines and power plants manage toxic chemicals that may pose a threat to people and the environment. A lot of chemicals are managed through activities like recycling and treatment. But some are released to the air or water, or disposed of on land.

Hawaii is clean when it comes to toxic releases. The Aloha State ranked 44 of 56 states and territories in terms of total releases per square mile; a higher number means fewer releases. Also, the amount of toxic material managed by facilities dropped by 38 percent in 2018, driven by decreases in the petroleum products sector, the EPA reported.

And the situation might get better soon. That’s because three of the state’s five dirtiest facilities are power plants, including a coal-burning electric plant slated to close in 2022.

“Each year Hawaiian Electric is adding more grid-scale and customer-sited renewable energy to its island grids,” said Shannon Tangonan, a Hawaiian Electric Co. spokeswoman. “When our power purchase agreement with the AES coal plant ends in 2022, Hawaii will be one of three states that do not burn coal to make electricity.”