Officers responding to a 911 call for one person suffering chest pain in a medical emergency ultimately found three adults and two children who had been exposed to more than 300 ppm of carbon monoxide around 10:30 p.m. on Elm Grove Circle in Cloverly, the county's fire department said.
The source of the CO was found to have been charcoal burners used for a ceremony indoors with poor ventilation.
According to the Consumer Product Safety Commission, "most people will not experience any symptoms from prolonged exposure to CO levels of approximately 1 to 70 ppm but some heart patients might experience an increase in chest pain.
"As CO levels increase and remain above 70 ppm, symptoms become more noticeable and can include headache, fatigue and nausea. At sustained CO concentrations above 150 to 200 ppm, disorientation, unconsciousness, and death are possible."
It was not immediately clear how long the family had been exposed.
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