A man and two companies in Alaska have been sentenced to three years probation and a $35,000 fine for violating the Clean Air Act involving asbestos work at a shopping center more than five years ago, a judge said.

The work was performed at the Northern Lights Center in Anchorage, the former location of an REI store. Reports of potential asbestos exposure at the time closed the store for a day back in 2015, authorities said.

U.S. District Court Judge Joshua Kindred sentenced Tae Ryung Yoon, 64, on Friday to probation, fined him $35,000 and said he owes $30,000 in restitution for medical monitoring of the four workers who claimed they were exposed to asbestos, the Anchorage Daily News reported.

The owners of Yoo Jin Management Company Ltd. and Mush Inn Corp. were also sentenced after agreeing to plead guilty to a charge of violating the Clean Air Act’s Asbestos Work Practice Standards. Both companies are owned by Chun Yoo, who is in his 80s and has “serious medical conditions,” and his wife, attorney Kevin Fitzgerald said. The couple still owns the center.

The case centers on workers who said they were exposed to asbestos during improperly conducted renovations involving an old boiler room. The work was stopped when two of the workers raised concerns.

High levels of asbestos exposure can cause lung disease or cancer.

Prosecutors said in a statement that the building owners and manager relied on a contractor who was not a certified asbestos abatement contractor and “failed to inform the contractor of the possibility of asbestos in the old boiler room.”

Fitzgerald argued that an assessment indicated no evidence of asbestos when his clients bought the center in 2006. Yoon was the building’s property manager at the time.

Documents show the boilers were replaced by another company in 2012 and the old ones were removed in 2014 to make more room. Some of the workers took photos of what they thought was asbestos and emailed them to the property management company that employed Yoon.