Baltimore County, MD- Baltimore County firefighters returned yesterday to the marina where three people recently died of carbon monoxide exposure to talk to boaters about the dangers of the deadly gas.

The boatside visits at Parkside Marina in Bowleys Quarters are part of the county’s holiday week plan to visit about 20 marinas to distribute information and encourage people to equip their boats with carbon monoxide detectors – inexpensive devices that could have saved the lives of the victims of the June 18 poisoning at the marina.

Such alarms are not required by law – as smoke detectors are – in homes or boats, but fire departments strongly encourage people to install them.

Carbon monoxide, as firefighters explained yesterday to early risers who were cleaning equipment or sipping coffee on boatdecks, is a colorless, odorless gas produced by fuel-burning appliances. Initial symptoms of poisoning are headache, fatigue, nausea, dizziness and shortness of breath. If carbon monoxide makes up just 1 percent of the atmosphere, a person can die within minutes, said battalion chief James Devers. Nationwide, more than 200 people die each year from carbon monoxide poisoning, he said.

The Fire Department began the first-time campaign yesterday because the holiday typically kicks off the busiest boating weekend of the year. The “Boater Safety Days” program days will continue through July 8.

People at the docks were receptive to yesterday’s safety lectures, though most had two or three detectors on their boats.

Mick Witherow, who was working on his sailboat, was one of the few whose boat was not outfitted with a carbon monoxide detector. Firefighters explained that the diesel engine on his 33-foot sailboat, Liberty, made him vulnerable to poisoning.

“I’m certainly going to look into it,” he said.

Firefighters believe carbon monoxide from a generator caused the deaths of Laura Jean Gladden, 34, of Middle River, John Elijah Marsh, 40, of Dundalk and Patty Mae Vento, 42, of Plantation, Fla., said Capt. Lawrence Majchrzak. It is not clear why the victims, who apparently died in their sleep, were using a generator because docked boats have access to electric power supplied by the marina, he said.