A recent string of injuries and deaths across the country has brought attention to the dangers of carbon monoxide poisoning, especially during colder months.
One incident of possible carbon monoxide poisoning in Ohio left two people dead last Friday, according to ABC's Dayton, Ohio affiliate WKEF. High levels of carbon monoxide were detected in the home where the woman and man were found dead, officials said.
Authorities in Parks, Arizona, found a family of four, including two children, dead inside their home on New Year's day, according to ABC News affiliate KNXV. Investigators hired a licensed heating and cooling provider and found a major failure with the in-home heating system, which officials said would be consistent with carbon monoxide poisoning.
Ten people were hospitalized on Monday after their St. Paul, Minnesota, home had dangerous levels of carbon monoxide, according to ABC News affiliate KSTP.
The U.S. Center for Disease Control and Prevention (CDC) warns that as temperatures drop and in-house heating systems are turned on, the winter can be an especially dangerous time since space heaters, generators and other portable heating devices can leak carbon monoxide.
Every year 400 Americans die from exposure to carbon monoxide, according to the CDC, with 4,000 hospitalized and 20,000 ending up in the emergency room as a result of exposure to the colorless, odorless gas.
The signs and symptoms of exposure can be subtle, leading people to try and sleep it off instead of heading straight for the emergency room. So here's the information you need to know to stay safe from carbon monoxide poisoning.
Sign and symptoms
Carbon monoxide can be deadly but its initial symptoms can be mild, starting off as just a headache and sleepiness.
Dr. Jerri Rose, the program director of Pediatric Emergency Medicine at Cleveland's University Hospitals Rainbow Babies and Children’s Hospital, said early symptoms, including fatigue, headache, nausea and short of breath, can often appear to be an early flu.
In severe cases, a person can become confused or faint due to the effects. In rare cases, death is possible.
Doctors may also notice a slight redness in the face or lips of a person with CO poisoning in rare cases, Rose said.
"In actual reality, few physicians ever see that," Rose said of the red face symptoms. "Generally there’s not really anything you can look at by telling someone."
Carbon monoxide safeguards
The CDC recommends that everyone have a carbon monoxide detector in their home. Rose suggests that people who live in a multilevel home have detectors for every floor of their home, similar to their smoke detector.
Common sources of carbon monoxide are internal combustion engines or heating sources. Every year, doctors hear stories of people killed by carbon monoxide as they tried to heat their homes, Rose said.
To protect against carbon monoxide poisoning, the CDC recommends that heating systems, water heaters and any other gas, oil, or coal burning appliances be serviced by a qualified technician every year. Make sure gas appliances are vented properly and never use a generator, camp stove or oven as a heater indoors.
A full list of advice from the CDC can be found here.
How does carbon monoxide poisoning work?
When the body absorbs carbon monoxide, these molecules bind up the hemoglobin in the red blood cells. This makes it impossible for the red blood cells to carry vital oxygen and deliver it to organs and muscles.
There is no "safe" level of exposure to carbon monoxide, Rose said, and acute symptoms can occur in minutes or days depending on the level of CO exposure.
Doctors usually treat carbon monoxide by giving the affected person oxygen through a mask, according to Rose.
In extreme cases, doctors can rush a patient to a hyperbaric chamber, which can help raise blood oxygen levels more quickly since the pressurized environment allows the victim to inhale more oxygen molecules with each breath, Rose said.
Early treatment is critical, according to Rose, who said patients shouldn't be afraid to get help for symptoms that may appear minor.
"It’s important for people to be aware if they have any symptoms at all, they should come in and get checked out," she said. "If they suspect that they could be [exposed] it could be very life-threatening to not seek medical attention, especially in winter time."
Some of the information in this article was originally published in 2015. ABC News Gillian Mahoney contributed to this report.