A New Zealand man "blew up like a balloon" in a freak accident.

Truck driver Steven McCormack slipped and fell from his vehicle's foot plate, breaking a compressed air hose that powered the brakes.

He fell so hard onto the brass fitting, it pierced his buttock and pumped air into his body.

Steven recounted: "I felt the air rush into my body and I felt like it was going to explode from my foot. I was blowing up like a football.

"I had no choice but just to lay there, blowing up like a balloon."

The 48 year old was taken to hospital after workmates heard his screams and released him from the air flow.