Prince George's County will begin operating its seventh mobile intensive care unit, for emergency treatment of heart attack and accident victims and others needing critical care, in Largo in May, County Executive Parris Glendening announced yesterday.

Staffed by 10 paramedics at the Kentland Fire Station, the medical operation will be directly responsible for an area of about 40,000 people and will cost $375,000 to initiate and $300,000 a year to maintain, said Fire Chief James Estepp. Compared with ambulances, the paramedic units have more sophisticated life support equipment and personnel with more training ambulance crews, Estepp said.

They are sent in response to calls concerning such emergencies as heart attacks; car accidents with serious injuries; breathing trouble; violent assaults; train, plane and bus disasters, and multiple-alarm fires.

Glendening said yesterday that he plans to include a proposal for an eighth paramedic unit in his budget for the fiscal year beginning July 1, which will be presented to the County Council March 31. Eventually, the county government hopes to operate 12 paramedic units, he said.

"Each unit represents 40 additional lives that could be saved every year," Estepp said.

The new unit will serve residents of Largo, Kettering, Seat Pleasant, Glenarden, Woodmore and Upper Marlboro. Major facilities in the area include the Capital Centre, Wild World and Prince George's Community College.

One of the county's six existing intensive care crews needs up to 15 minutes to reach those areas, compared with an eight-minute response time expected after the unit is in operation, Estepp said.

Paramedic units are now located in Brentwood, Silver Hill, Laurel, Bowie, Clinton and Landover Hills.