Mayor Marion Barry said yesterday that the District is beginning to improve its ambulance response time and hopes by July 1 to have trained medical technicians aboard firefighting vehicles that also respond to 911 emergencies.

A spokesman for the firefighters union said later there was little new in what the mayor said and dismissed the announcements as largely a public relations attempt to improve the image of the troubled ambulance service.

Barry, standing in the bay of a fire station at Fifth Street and Rhode Island Avenue NE, released new city statistics that showed the city's average ambulance response time is 7.1 minutes from the time a vehicle is dispatched until it arrives on the scene -- similar, he said, to that of other major cities.

The city previously said the average response time was about 10 minutes, but officials said yesterday that calculation was made from the time a call was received on the 911 system until an ambulance arrived on the scene.

Barry said that the change in calculation was not an attempt to make the city look better, but to compare it more accurately to other cities. City officials said under the old calculation, the response time in April was about 8.7 minutes rather than 10.

"We've come a long ways, we've

made a lot of improvements" with more to be done, Barry said. Fire Chief Theodore R. Coleman, City Administrator Thomas M. Downs and other top public safety officials looked on during the media event, which was delayed while firefighters rolled emergency equipment into the station for the benefit of cameras.

Barry acknowledged that intense media scrutiny of the ambulance service had caused the city to focus more on its problems, but both Barry and Downs complained that the media had inaccurately compared the District to other cities that used different measuring systems.

"We're comparing apples and apples," Barry said. The figures showed similar ambulance response times for cities such as Cleveland, Boston, Oklahoma City, Milwaukee, San Antonio and Houston. Baltimore has a dispatch-to-arrival time of six minutes, a city chart showed.

Thomas Tippett, president of Local 36 of the International Association of Fire Fighters, said the promise of more emergency medical technicians is "a shell game" because they will not be allowed to transport victims to hospitals. "The fire truck gets there and stands by and waits for the ambulance."

City officials acknowledged yesterday that it had been fire department policy for five years to have a fire truck respond when no ambulance is readily available. They said the difference would be that the trained medical technicians would be available for preliminary care on the scene and to help determine whether an ambulance is needed.

Barry said that of the 120,000 ambulance calls received last year, about 50,000 did not require taking someone to a hospital.

Tippett said, however, that the city needs to change its laws to allow paramedics -- more highly trained than emergency medical technicians -- to respond to ambulance calls and have authority to cancel unwarranted calls. Under District law, a person with minor injuries, such as a cut finger, can insist on ambulance service and it must be provided, Tippett said.

Tippett praised Barry for calling for more public education on how and when to use city emergency services. "That's what every other major city does. We need three things: public education, paramedics to refuse ambulance service, and we need more ambulances."

Barry said yesterday that his officials are not persuaded that the city needs to increase its fleet of 21 ambulances, but would monitor results during the next few months. "If we need more ambulances, this mayor will provide them," he said.