Plans for a new type of paramedic who would treat patients in their homes could make hospital visits for minor injuries a thing of the past.
Ambulances would be reserved for life-threatening cases
The idea came from an ambulance service review, partly concerned with how to reduce patient numbers in hospitals.
Under the plan, ambulances would be reserved for emergencies, with cars or motorcycles sent to less serious cases.
But Ray Carrick from the Ambulance Services Unions said there were "health and safety difficulties" with the plan.
"If we've got staff going to an increased number of calls on their own, perhaps particularly female staff, then there are inherent difficulties attached to that and we need to be very cautious about how we approach it," he said.
Health Secretary Patricia Hewitt told the Sunday Telegraph as many as 90% of calls to the emergency service could be dealt with in ways other than by rushing the patient to hospital.
She told the paper: "If you are a mum and your child has fallen off his bike, you want him checked over but the last thing you want is to take him to A&E.
"The ambulance service can take on a new role by taking the hospital to you."
Speaking later on Sky News, she said the measure was not a cost-cutting move, but was instead a "real improvement" that many patients had said they wanted.
She said staff would receive up to two years of extra training to qualify for the new role.
"This is about reshaping the ambulance service... about using the staff we have got better, training those who want to get more skills up so that they can actually do more for patients."
The review, by national ambulance adviser Peter Bradley, will outline a five-year plan for developing the service.
It will say that up to one million patients a year are taken unnecessarily to accident and emergency departments.
The review, to be published on Thursday, will propose retraining some paramedics to enable them to perform tests, prescribe drugs and treat chronic diseases such as asthma and diabetes.
The new paramedics would be called "emergency care practitioners".