A gas grill accidentally left on overnight nearly resulted in a tragedy in the Eclipse neighborhood Saturday.

Mona and Kenneth Hendrickson, both 59, were rushed to Sentara Leigh Memorial Hospital in Norfolk from their home in the 9100 block of Wigneil Street after he called emergency dispatchers just before 1 p.m. to report he and his wife weren’t feeling well.

The dispatcher questioned the man about his symptoms as rescue personnel were on their way. About the same time, a friend responding to a call from the husband stopped by and found him in a confused state, city spokeswoman Diana Klink said in a press release.

Firefighters arrived at 1:08 p.m. and found the wife semi-conscious and collapsed on the bathroom floor, Klink said. Tests revealed an extremely high level of carbon monoxide in the home.

Rescue workers called for the Nightingale air ambulance while stabilizing the patients. The helicopter picked her up, and the husband was sent via ground ambulance. Both were treated in Sentara Leigh’s hyperbaric chamber, a treatment that delivers high amounts of pressurized oxygen to counter the effects of carbon monoxide poisoning and other ailments.

A search for the source of the toxic gas led rescue workers to the garage, where the gas grill the couple had cooked on Friday night had been stored after being left on accidentally, causing the home to fill with a dangerously high level of carbon monoxide poisoning.

Both patients were in good condition Saturday evening, a Sentara spokeswoman said.

Carbon monoxide is a colorless, odorless gas that is toxic to humans and animals. At lower levels of exposure, it cause headaches, dizziness, disorientation, nausea and fatigue. At higher concentrations, it can cause chest pains, impaired vision, reduced brain function and death, according to the Environmental Protection Agency.

Sources of carbon monoxide include unvented kerosene and gas space heaters, leaking chimneys and furnaces, back-drafting from furnaces, gas water heaters, wood stoves and fireplaces, gas stoves, generators and other gasoline-powered equipment, and automobile exhaust.

Moderately-priced carbon monoxide detectors are available in most home goods stores. The EPA also recommends these steps to prevent carbon monoxide from building up in your home:

• Keep gas appliances properly adjusted.
• Consider purchasing a vented space heater when replacing an unvented one.
• Use proper fuel in kerosene space heaters.
• Install and use an exhaust fan vented to outdoors over gas stoves.
• Open flues when fireplaces are in use.
• Choose properly sized wood stoves certified to meet EPA emission standards.
• Have a trained professional inspect, clean and tune up heating system equipment annually, and repair any leaks promptly.
• Never idle the car inside the garage.
• Never use a generator inside homes, garages, crawlspaces, sheds or other areas without full ventilation.