A proposal to require hard-wired carbon monoxide detectors in all Maine homes and hotel rooms is headed for the Legislature, and safety advocates hope an incident in which the colorless, odorless gas sickened 21 guests at an Ogunquit resort in February will provide the motivation to make it law.

“Out of something bad, we hope that something good comes about,” said John Martell, president of Professional Fire Fighters of Maine. “We hope that that type of thing brought the awareness to people that there’s a real danger.”

The president of the state firefighters’ union is working with Sen. Bill Diamond, D-Windham, sponsor of the state’s first carbon monoxide detector regulations in 2009, to bring forward a new bill this Legislative session. Martell, Diamond and others are scheduled to call for improved safety during a news conference Thursday.

Current Maine law says all rental units and newly purchased homes — as well as houses, hotels and dormitories built or renovated after Aug. 1, 2012 — are required to have carbon monoxide detectors to warn occupants about dangerous levels of the gas, which is a byproduct of burning fossil fuels. Martell wants to expand the requirement to all existing structures where people sleep.

“We’ve advocated for this since the inception of the law,” he said.

Martell said the existing regulations represented a compromise with opponents and that several bills to expand the law have been proposed since then, including one last session that would have required carbon monoxide detectors in schools. It never made it out of committee.

Maine law initially focused on rental units and homes that change owners. It was amended in 2011 to include new construction.

After the carbon monoxide leak at The InnSeasons Resorts — The Falls at Ogunquit in February, Martell thinks legislators now might see the need to expand the law to include other existing structures.

The resort guests were sickened when the gas leaked from a broken pipe intended to vent fumes from a propane furnace.

The leak was found after several guests in different rooms reported feeling nauseous, getting headaches and passing out. A desk clerk called the Fire Department, and firefighters found carbon monoxide levels that were nearly 10 times what would have set off a detector. Seven of the guests were taken to area hospitals for treatment.

Signs of carbon monoxide poisoning include headache, nausea, vomiting, dizziness, drowsiness and confusion, according to the Maine CDC. Exposure to high levels of the gas can be fatal.

The owners did not face sanctions for not equipping the resort with carbon monoxide detectors because it was built in 1988 and was exempt from the requirement.

General Manager Heather Ault said Wednesday the resort has installed carbon monoxide detectors since then. She could not provide details Wednesday about how many or how much they cost.

Greg Dugal, executive director of the Maine Innkeepers Association, has said the cost of wiring in a carbon monoxide detector, which might require interior renovations, has been estimated at $1,000 per room. He also has said many hotels use electric heat and air conditioning, with no combustion to produce carbon monoxide.

“Hard-wiring every hotel room in the state with a carbon monoxide monitor, that would be unreasonable, in my opinion,” Dugal told the Portland Press Herald shortly after the February incident. Dugal was out of state Wednesday and couldn’t be reached for comment.

Martell said a less expensive option for hotels is to replace hard-wired smoke alarms, which most already have, with combination smoke and carbon monoxide detectors that cost as little as $25.

While such a requirement would affect many homes and apartment buildings across the state, a majority of single-family homes and apartment buildings in Maine already have them.

In the year after the 2009 law was enacted, the percentage of rental units in the state with carbon monoxide detectors jumped from 34 percent to 58 percent, according to the Maine Center for Disease Control and Prevention. Last year, about 69 percent of rental units and 64 percent of single-family homes had carbon monoxide detectors.

Meanwhile, incidents of carbon monoxide poisoning in the state appear to be dropping.

After 153 emergency department visits for carbon monoxide poisoning in 2008 — the highest number since at least 2001 — the visits dropped to a 10-year low of 93 in 2010, followed by 97 visits in 2011, the last year for which figures are available.

Annual carbon monoxide deaths in Maine between 2000 and 2010 ranged from zero to five. Nationwide, carbon monoxide killed an average of 430 people a year between 1999 and 2010, according to the federal CDC.

The highest rate of carbon monoxide poisoning in the U.S. was in the Midwest, followed closely by the Northeast.

According to the National Conference of State Legislatures, 29 states have carbon monoxide detector requirements, which apply to everything from buildings with fossil fuel burning equipment to all hotels, schools and single-family homes.

Martell said carbon monoxide detectors are especially crucial in Maine, where power outages are frequent and many people use generators for backup.

The winter also poses a greater risk for carbon monoxide poisoning because of the use of heating units and the fact that homes are more tightly sealed.

In addition to proposing legislation, Martell and Diamond are working to increase awareness about carbon monoxide poisoning and access to detectors through donations. They, along with fire chiefs and other legislators from Windham and surrounding towns, will talk about those plans at 11 a.m. Thursday at the Windham Public Safety Building.