ORONO, Maine — Area residents said Tuesday night that they are worried about how plans to increase air pollutant emission limits at Old Town Fuel and Fiber will affect their health, quality of life and home values.

About 20 locals attended Tuesday night’s meeting at the Black Bear Inn in Orono, which was scheduled by the Maine Department of Environmental Protection to allow residents to voice their concerns about the hike in the levels of carbon monoxide and sulfur dioxide emissions.

The meeting came a month after the DEP issued a draft license that would bump the Old Town pulp mill’s carbon monoxide emissions cap from 407 tons per year to 929 tons.

Old Town Fuel and Fiber had requested that its limit be increased to 1,045 tons per year.

Exposures to carbon monoxide — a toxic, odorless, colorless gas — can cause harm to the heart and central nervous system, but several residents at Tuesday’s meeting said they were concerned about potential odor and adverse health conditions caused by sulfur dioxide.

The DEP decided sulfur dioxide emissions also will be allowed to increase, from 97 tons to 111 tons per year.

Bill Thompson, air quality program manager for the Penobscot Indian Nation, said he was concerned that relaxing pollution rules would prompt the mill to continue to exceed its limits. He used the analogy of increasing an interstate speed limit from 65 to 75 mph, which doesn’t prevent people from speeding but instead allows them to travel faster.

“Just because you’re allowed to doesn’t mean you should,” he said.

Orono resident Sam Hunting said he was “shocked and appalled at the lack of due diligence that’s been displayed in this process.”

He argued that the DEP should look to local hospitals to see how many illnesses and hospital visits are attributed to mill emissions.

Hunting also worried about how the increased sulfur emissions might affect the odor in town and drive down the value of his home.

John Banks, natural resources director for the Penobscot Nation, said he was concerned the emissions might have a negative effect on the Penobscot River, which is in the midst of a $62 million effort to restore the waterway and boost migratory fish populations.

The emissions cap increases aren’t final, and if DEP Commissioner Patricia Aho issues final approval following the public comment period, her decision could still be appealed to the Board of Environmental Protection, a citizen group that oversees the DEP.

At Tuesday’s meeting, Old Town resident Ed Spencer called on the DEP to hold a public hearing that would include members of the department as well as officials from Old Town Fuel and Fiber. He argued that the mill has a “long history of noncompliance” and that the public should be allowed to ask questions of the owners.

Carbon monoxide and sulfur dioxide emissions originate from the mill’s aging biomass boiler, which was manufactured in 1986 and installed at the mill in 2004, according to the DEP license draft.

That boiler, which originally burned construction demolition debris, switched to green wood, which has a higher moisture content and doesn’t burn as cleanly, leading to an increase in emissions, according to Eric Kennedy of the DEP’s Bureau of Air Quality.

A “proposed administrative consent agreement” from the DEP revealed in November 2011 that the department was prepared to issue a $497,000 fine to Old Town Fuel and Fiber for exceeding its air pollution limit over a 12-month period.

That would come on top of $331,000 in penalties for emissions cap violations assessed by the DEP and the federal Environmental Protection Agency on the mill in the past five years.

Mill officials have said the boiler would be too expensive to replace and that the amount of emissions is a small price to pay for keeping the mill running.

“We’ve been hearing for eight years that this boiler merely needs some fine-tuning,” Ed Spencer said.

“It’s not that we want to see the mill leave,” Old Town resident Cheryl Spencer said, “but we want cleaner air and better technology.”

Maria Girouard of Orono didn’t share that sentiment, recommending that the DEP look at industrial projects and how they affect the environment collectively rather than individually.

“Our state is being turned into an industrial wasteland, and this is just one piece of it,” she said. “I think the facility should be shut down.”

Melanie Loyzim, the DEP air quality bureau director, has said the department’s computer modeling shows the pollution will be dispersed well enough so as not to violate the EPA’s National Ambient Air Quality Standards.

During the meeting, the DEP announced that the public comment period would be extended to 5 p.m. Friday, Aug. 24, to allow more people to provide their thoughts on the emissions cap increase. Letters may be sent to Kathy Tarbuck at the Bureau of Air Quality, 17 State House Station, Augusta, 04433.

Lance Tapley of the Maine Center for Public Interest Reporting contributed to this report.