People Express Airline said yesterday that it will begin its new nonstop service between Baltimore/Washington International Airport and Newark International Airport, offering the lowest fares available between the two metropolitan areas.

The two-month-old Newark-based airline said it will charge $35 on weekday flights departing before 7 p.m. and $23 each way on flights departing after 7 p.m. on weekdays and on all flights on Saturday and Sunday. People Express plans to begin its service with six daily roundtrips on July 15.

Other airlines generally charge between $59 and $79 for nonstop flights to New York or Newark. New York Air's fares and $49 and $49 on its two tier pricing structure on flights between Washington's National Airport and New York's LaGuardia, and the airline plans to extend those fares to its new Newark service from National, also starting July 15.

People Express official Harold J. Pareti told reporters at BWI yesterday that the new airline, which flies 118-seat Boeing 737 jets, will offer 9,000 seats a week between BWI and Newark, with 3,500 of them at the lower fares.

The airlines brings to the Washington area a new kind of service prompted by deregulation. Organized by former officials of Texas International Airlines, People Express has eliminated ticket counters, airline food and the baggage check-in and pick-up provided by other carriers. "These are considered 'free' items, but there are costs associated with each one," Pareti said.

On People Express, passengers make reservations by phone, but at the airport they go directly to the gate for a boarding pass. Tickets are paid for on the plane during the flight, as on Eastern's Air-Shuttle. Passengers can check baggage for an additional $3 charge but are encouraged to carry their luggage.