All too often, people succumb to carbon monoxide produced by generators when the power goes out during a storm. Even if you know not to run one inside, plenty of homeowners trying to be safe with generators get overtaken by the colorless, odorless, tasteless fumes.

Think it’s safe to run your generator in the garage with the door open? Or outside but close to the house? Don’t do it — even if you’ve done it before, according to state toxicologist Dr. Andy Smith.

Smith originally spoke to the Bangor Daily News in July 2015 following the the deaths of four young people in Byron from apparent carbon monoxide poisoning. But his warnings remain relevant as Maine battles a powerful storm that hit Sunday night and continues to leave nearly half a million residents without power.

Generators spit out an alarming amount of carbon monoxide. Just one can produce the same amount as 100 cars, according to the National Institute of Standards and Technology.

“Imagine that you have tubes going to the exhaust of 100 cars,” Smith said in 2015. “Would you want all those tubes to empty into your garage? Or would you want them all sitting just outside your window?”

The direction of the wind and how your house breathes on any given day can significantly affect the buildup of carbon monoxide inside, he said. Dangerously high concentrations can accumulate within minutes.

“It’s like playing Russian roulette,” Smith said. “Maybe nine times out of 10 you can operate it in your garage and not have any issues if you’ve got the exhaust pointing out and it’s right at that doorway. But what about that one time where it doesn’t work out because of the wind direction and the way your house is pulling in air?”

Maine has recorded severe poisonings from homeowners refueling generators in poorly ventilated areas, after doors or bulkheads accidentally close, or when people leave doors slightly open to let in an extension cord, Smith said.

After a spate of carbon monoxide poisonings during the ice storm of 1998, Smith and some of his colleagues estimated the risk of poisoning if a generator is operated in an attached structure, like a garage, compared to outside. They found a 19-fold increase in risk.

Generators aren’t going anywhere. So where should we put them? It’s not a simple answer.

“Generators have these two messages on them: One the one hand ‘operate with adequate ventilation or only operate outside,’ and then right next to that it will often tell you ‘but only use in dry conditions so you don’t get electrocuted,’” Smith said.

If you’re keeping it dry, you might have a ventilation problem. If it’s in an area that’s well ventilated, it might be exposed to the elements.

Make a plan for using your generator

Ideally, make a plan to shelter your generator — before it’s dark and stormy outside.

— Never use a generator inside, even in an attached structure like a garage or barn.

— Place generators at least 15 feet from your house. Make sure you have a long enough extension cord that’s in good condition.

— Point the exhaust away from your home and any windows, doors or vents.

— Keep generators dry to avoid the risk of electrocution and cool to prevent overheating.

— Install generators according to the manufacturer’s instructions. Improperly installed generators can put electrical line and emergency workers at risk by back feeding and energizing power lines without warning. Relay switches shut off the power coming from the road to avoid that hazard.

— Decide if you will leave your generator in its shelter or shed or drag it out each time a storm hits.

— Never refuel a generator while it’s running.

— Install carbon monoxide detectors powered by batteries or with a battery backup. (Only about 60 percent of Maine residences have CO detectors.)

Symptoms of carbon monoxide poisoning

Also know the symptoms of carbon monoxide poisoning, which could be your only warning if you don’t have a working detector. But be aware that if you’re sleeping or intoxicated, you can die without experiencing any signs.

— Headache, dizziness, weakness

— Upset stomach, vomiting

— Chest pain

— Confusion

Up to 40 percent of carbon monoxide poisoning survivors may experience neurological complications, such as memory loss, dementia, a Parkinson’s-like syndrome, or even psychosis, according to Maine CDC.

While generators are a major culprit in carbon monoxide poisonings, cars, small engines, stoves, fireplaces, grills and furnaces also produce the dangerous gas.

I'm the health editor for the Bangor Daily News, a Bangor native, a UMaine grad, and a weekend crossword warrior. I never get sick of writing about Maine people, geeking out over health care data, and...