Ambulances and paramedics were called to SE Tyres on Tarring Road at just after 9am on Tuesday morning after the accident, involving a male member of staff.
Police and fire crews also attended the incident.
A spokesperson for the South East Coast Ambulance Service (SECAmb) said they believed the man had been struck on the head while working, suffering potentially serious head injuries.
Paramedics treated him at the scene before he was taken to the Royal Sussex County Hospital in Brighton.
“We were called to a report of an explosion at a business unit in Tarring Road, Worthing at 9.01am this morning (November 27).
“Two engines were sent to the scene. On arrival, it was established there was no fire or explosion.
“Fire crews left the scene at 9.38am after making sure the area was safe.”
A West Sussex Fire and Rescue spokesperson