Police said the man was travelling east in a minivan when he crossed the centre line and struck a Chatham-Kent ambulance.
Two paramedics, a 36-year-old Chatham woman and 46-year-old Chatham man, were in the ambulance. There were no patients on board.
The female driver was taken to Hotel-Dieu Grace Hospital with serious lower body injuries.
On Monday, Logan Simpson, 25, of Wheatley, was arrested and charged with dangerous driving causing bodily harm.
He was released pending a future court date.