While on standby with a lot of other units at an airport for an airliner with multiple unconscious passengers reported, I noticed I had a headache. It was a large response and all the vehicles were idling while we waited for the HazMat crew to assess the planes atmosphere. Several others replied they had headaches too and I realized that we were all getting CO poisoning. We cleared soon after but I got nauseous when returning but we got picked up for another call. Just wonder how close we came to a real mass casualty event. Only 1 passenger had passed out after vomiting the rest were sympathetic vomiters.
LESSONS LEARNED:We need to shutdown or stay upwind of our vehicles in staging areas.
