EVERETT — Gail Evert held the glass flask to her nose and sniffed.

She could smell trace amounts of butanol, a kind of alcohol, in the liquid solution. Evert, 51, took a whiff from two others to be sure she could name the one with the most intense smell.

“It’s definitely this one,” Evert said, pointing out a flask.

The Everett woman was one of 17 people who attended a training-and-screening session Tuesday night at the Snohomish County PUD building to volunteer their sense of smell for an odor study.

Many people in Everett and Marysville have long believed that a stench that has permeated their neighborhoods is coming from Cedar Grove Composting, a company based on Smith Island. The goal of the $453,600 study is to find out if they’re right.

Volunteers took three tests to determine whether they have a normal sense of smell.

One test consisted of identifying the strongest variation of three butanol solutions in 10 rows; another had volunteers group odors according to intensity. For the third test, volunteers smelled bags filled with 11 odors. Odotech workers collected smells in the plastic bags from asphalt, low tide, beauty bark, rotting compost and other smells.

“It was a very interesting process to determine my perception of smell,” Evert said. “I’m willing to participate because it’s not just about me, it’s all my neighbors. Someone has got to step up.”

The results of the tests will enable the company to select people to be part of an odor committee, said Thierry Page, CEO of Montreal-based Odotech.

The volunteers over the course of a year will be responsible for recording what they smell in the air near their homes. They’re expected to begin in early October. The company is still looking for volunteers from Tulalip and Lake Stevens.

“We don’t have anyone from those areas,” Page said. “We hope we can get as many (volunteers) as possible. The goal is to accept people, but we need to have people with a normal sense of smell.”

The information recorded and collected from committee members will be combined with data taken from six electronic odor detectors, called “e-noses,” which will be placed in locations throughout the Snohomish River Delta. The e-noses will be near suspected sources of odors, but the exact locations haven’t been decided, Page said. Cedar Grove agreed to share results from four e-noses on their property to be included in the study, he added.

“None of the six will be at Cedar Grove. They will be at other facilities,” Page said. “There are numerous sources, and it’s important to pick the right locations.”

Odotech was hired by the Puget Sound Clean Air Agency. Inspectors with the agency several times have traced the smell to Cedar Grove.

The company has been fined several times for odor violations at the Everett plant and another plant in Maple Valley in King County. More data must be collected, said Joanne Todd, a spokeswoman for the Puget Sound Clean Air Agency.

“We really need to understand where the odors are coming from,” she said. “We have to take a high road and we have to take the correct road. We need a study to identify what smells are out there.”

The agency is working on a website where it will post information about the study throughout its duration, Todd added. Final results are scheduled to be released in November 2013.

Cedar Grove is putting up $200,000 — fines paid by the company for odor violations — toward the cost of the study. The city of Seattle and King County, which both send yard and food waste to Cedar Grove for composting, are contributing $100,000 and $50,000, respectively. The Department of Ecology is contributing $78,600 and the Clean Air Agency is spending $25,000.

Marysville resident Dean Maas said the tests were interesting but he already believes the rotting smell in the air near his home is coming from Cedar Grove Composting. He wants to be part of the odor committee to find a solution to the stench.

“I just want to do whatever I can to get the smells resolved,” he said. “I’m pretty convinced that I know where it’s coming from.”

Ron Lambert, 70, has for the past two years kept a journal of when he smells the odor that he, too, believes is coming from Cedar Grove. The Marysville man is skeptical the study will name a definitive source of the odor, but he would like to be a part of the committee.

“Why should they have to study for a year and analyze it for a year when they already know what the problem is?” he said. “There’s Cedar Grove and then there’s not.”

Amy Daybert: 425-339-3491; adaybert@heraldnet.com.