Sad news reports from the aftermath of winter storm Jonas underscore an important lesson about the dangers of sitting in a sealed, parked car with the engine running.

One tragic incident involved a New Jersey woman and her one-year-old son, both of whom died of carbon monoxide poisoning after sitting in their snowed-in car with the engine running, the New York Times reports. They were watching her husband shovel the vehicle out of its parking space. The exhaust pipe was still buried in the snow, causing carbon monoxide to build up inside the car. The husband found them unconscious and called 911.

Carbon monoxide is a colorless, odorless gas that can build up in the air and poison the people who breathe it. It’s found in the fumes from burning gas, wood, propane, charcoal and other fuel, according to the Centers for Disease Control and Prevention (CDC).

Related:Carbon Monoxide Poisoning: Is Your Family Protected?

More than 400 people die from carbon monoxide poisoning in the United States each year, with many of those deaths happening in winter, the CDC says. The symptoms of carbon monoxide poisoning are flu-like and include headache, dizziness, weakness, shortness of breath, upset stomach, vomiting, chest pain, blurred vision and confusion.

To prevent carbon monoxide poisoning, don't leave your car engine running if the car is covered in snow, according to the New Mexico Poison Drug and Information Center. Never leave a car running in a garage, even if the garage door is open. And never sleep in a parked car with the engine running, according to the Carolinas Poison Center.

Related: 8 Ways to Prevent Carbon Monoxide Poisoning After a Superstorm Hits

Beware of blocked exhaust pipes at home, too. Make sure your furnace, dryer and stove vents and exhausts are clean and unobstructed. Recently, seven residents of a Virginia apartment complex were hospitalized with carbon monoxide poisoning, NBC Washington reports. The cause: Vents in the furnace room were completely blocked by snow.

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Angela is a Pulitzer Prize-winning digital editor with more than 15 years of experience delivering news and information to audiences worldwide. Prior to joining SafeBee, she was the features editor for Boston.com at The Boston Globe, overseeing health, travel, entertainment, business and lifestyle coverage. Before moving to features, she was the news and homepage editor, covering stories such as the Boston Marathon bombing, Red Sox World Series victories, presidential elections, a papal inauguration, and more. Her favorite safety tip: Clean your phone! The average cell phone has 18 times more germs than the toilet handle in a men’s restroom.