Vail, CO – Members of five Nebraska families suffered carbon monoxide poisoning on a weekend ski trip to Vail, Colo.

The gas came from a faulty furnace in the house where they were staying, according to a press release from the Nebraska Medical Center. The families were treated at a Colorado hospital.

Unintentional carbon monoxide poisoning kills more than 400 Americans and sends 20,000 people to emergency rooms every year, according to the Centers for Disease Control and Prevention.

The Nebraska Regional Poison Center received 310 calls about the poisonous gas in 2013.

Carbon monoxide has no color, taste or smell. Symptoms of carbon monoxide poisoning include sleepiness, headaches, dizziness, blurred vision, nausea, shortness of breath and convulsions.

Many household items including gas- and oil-burning furnaces, portable generators, charcoal grills and cars turned on while in the garage produce carbon monoxide. To help prevent carbon monoxide poisoning:

• Have a professional inspect all fuel-burning equipment yearly.

• Make sure fuel-burning heaters are properly vented.

• Do not use a gas range or an oven to heat a room.

• Never use a charcoal grill inside.

• Install carbon monoxide alarms on every level of your home. Do not plug them in behind furniture or drapes.

• Never leave a car running in an attached garage, even with the garage door open.

• Have your vehicle’s muffler and tailpipes checked regularly.