The 4-year-old Ormondville boy flown to Palmerston North Hospital on Friday had inhaled so many petrol fumes he had passed out.
"We don't see this sort of situation in children often but, because there can be secondary problems, we were being extra cautious," Steve Yanko, of the St John Ambulance, said. "When the call came in, it sounded pretty serious but, by the time we got there, he was conscious and feeling a bit better."
Mr Yanko said the area was quite remote and there was no suitable landing spot for the helicopter so they had to transport the boy to a nearby road.
"My understanding is he was feeling very sick but, by the time we airlifted him out, he was feeling a lot better and got to enjoy the ride."
Palmerston North Rescue Helicopter pilot Marc Bridgman said the boy was checked by St John staff who decided not to take any chances and call the service rather than take him to the local hospital.