Two EMTs having dinner at an Applebee's restaurant on Long Island found themselves suddenly back on the job Tuesday night when their portable carbon monoxide detectors went off.
Justin Gau and Kyle Page told ABC 7 that their detectors went off as they were walking to their seats.
"I made Justin go outside once or twice to reset it to make sure it was functioning before we screwed up everyone's evening," Page told the station.
When they confirmed that the sensors were working, Gau and Page ordered everyone out and called the fire department, Patch.com reported.
About 100 patrons and employees were evacuated. Several said they felt sick and were checked out at the scene, but declined further treatment.
Air samples confirmed that CO levels in the restaurant were far above normal, with the problem later traced to a faulty water heater.
The average carbon monoxide level in a home without a gas stove is between 0.5 ppm and 5 ppm, and up to 15 ppm in homes with properly adjusted gas stoves, according to the EPA.
However, levels in the restaurant ranged from 80 ppm to 250 ppm -- or high enough to cause potentially serious or even deadly consequences.
According to the Consumer Product Safety Commission:
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.
"After they closed up, they shut down the ventilation system and the CO could have been pumping in there all night and whoever opened in the morning could have been a bad turn out," Page told ABC7.
Thanks to the EMTs, the heater was shut down and the building was ventilated.
The station says the restaurant does not have a CO detector.