The remains of a warehouse smolder at the former Lincoln paper mill on Thursday.

LINCOLN, Maine — State environmental safety workers will do air tests after two buildings were destroyed by a fire at the former Lincoln paper mill that police said was intentionally set.

The tests set for Saturday will determine the level of threat posed by cancer-causing pollutants found at the former Lincoln Paper and Tissue LLC mill. U.S. Environmental Protection Agency and Maine Department of Environmental Protection workers will tour the site on Friday, DEP spokesman David Madore said Thursday.

Maine’s environmental watchdog agency can not “give absolute assurances at this time” that the firefighters who fought the fire on Wednesday night, or the general public, is safe from the pollutants, Madore said.

Lincoln officials voted to seek a Superfund designation for the site earlier this year to handle the estimated $20 million cleanup of its asbestos, dioxin/furan, metals and Polychlorinated Biphenyls, or PCBs.

Lincoln officials are not aware of any immediate threat to public health caused by the site or the fire, said Dan Summers, Lincoln’s public safety director, on Thursday.

Firefighters from 10 towns and the Maine Forest Service doused fires that gutted a scale shed and destroyed a 300-foot-long warehouse on Wednesday. A former mill worker, David Parsons, 59, of Lincoln, was charged Thursday with three counts of arson.

“We have advised local firefighters to wash down their turnout gear in order to minimize exposure,” Madore said in an email on Thursday.

Saturday looks to be the best day for air testing, Madore said.

Rain is expected overnight Thursday and possibly into Friday, but clearing skies are forecast for Saturday.

“Keeping the material wet is the best short-term solution in order to limit” contamination, Madore said.

Earlier tests showed that asbestos on-site, used as a common industrial fire insulant, was the most prevalent toxin — heavy enough that the town’s attorney called the site the worst he had seen in a 35-year career.

The dioxin and PCBs came onto the site from pulp and papermaking processes.

It is unclear whether any cleanup occurred since the Lincoln Town Council vote, in March, or how much protection firefighters got from the self-contained breathing apparatus they wear.

The site’s level of contamination is well-known — it is primarily of 262 acres of the 387-acre site — and no injuries were reported from the fire.

Police believe Parsons started three separate fires at the mill, Maine Department of Public Safety spokesman Steve McCausland said, but are still investigating a motive.

Investigators from the state fire marshal’s office were on-scene for several hours on Thursday.

Demolition workers from M and M Consulting and Contracting of New Jersey were on-scene on Thursday. One was wearing a paper air mask, per standard procedure, not because of the fire, he said. Two were not.

“We haven’t been told anything” of any potential health threats, one said.

A fire accidentally occurred at a defunct mill site in East Millinocket in in March, that, like Lincoln’s, was being worked on by a demolition crew. The fire broke out in a pile of “debris and junk,” officials said.

An East Millinocket town official labeled the fire “toxic” because of the high level of contaminants on-site, but no illnesses arising from them were reported.

The Lincoln paper mill filed for Chapter 11 bankruptcy protection in September 2015, eventually laying off 128 workers employed there at the time. A boiler explosion in November 2013 left the mill leaking cash by ending Lincoln Paper’s ability to make pulp and paper.

The property’s owners sought bankruptcy court permission to begin marketing the site in August.

Firefighters from Burlington, East Millinocket, Howland, Lee, Lincoln, Lowell, Mattawamkeag, Milford, Passadumkeag and Springfield reportedly responded to the blaze, as did the Maine Forest Service.

BDN Writer Alex Acquisto contributed to this report.

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