An unintentional carbon monoxide poisoning incident that left one dead, seven hospitalized, is yet another reminder of the need for regular tests for carbon monoxide in homes.

Crews were called at 8:20 a.m. to a home in Anchorage, Alaska on Feb. 20. Responders found one man dead. Seven other residents were transported to the hospital. The residence was a single-family dwelling where one family lived. The source of the gas remains under investigation. Firefighters found 1,000 parts per million in the house, an unusually high amount, authorities reported.

Tragedy for Alaskan Family

Police later identified the deceased as 18-year-old Trevor Noble, according to US News.

“We were called originally for a cardiac arrest for one of the patients,” AFD’s deputy chief for operations, Jodie Hettrick, told the Alaska Dispatch News. “It was not reported as a CO call, and then when our crews got on scene we determined that there was more going on.”

Roughly every 10 years, over 400 people die from carbon monoxide poisoning, according to the Centers for Disease Control and Prevention. Experts recommend home air testing units in all home dwellings, and to have them regularly inspected on an annual basis.

The EPA recommends acceptable levels for carbon monoxide testing to be 50 parts per million (ppm) parts of air (55 milligrams per cubic meter) as an 8-hour time-weighted average (TWA) concentration [29 CFR Table Z-1].