ANNAPOLIS, FEB. 17 -- The Maryland House of Delegates passed legislation today that would require automobile owners to continue having their car emissions tested for pollutants -- but every two years instead of annually.

The measure, if approved by the state Senate, also would extend the tests to certain trucks and older cars, make it more difficult for owners to obtain waivers if their vehicles failed on the first try, and add inspections to ensure that drivers have not tampered with antipollution devices.

Without new legislation, the state inspections would lapse at the end of this year.

Maryland has required the tests since 1984 in its metropolitan areas, including the Washington suburbs, to ferret out cars that were causing ozone and carbon monoxide levels to exceed the standards set by the U.S. Environmental Protection Agency.

Although the state's air quality has improved since the tests began, it still fails to meet the federal standards in the Washington and Baltimore areas. If Maryland dropped the tests, it would risk losing federal funds for building roads, according to state environmental officials.

This morning, the delegates voted 117 to 7, without debate, in favor of the measure, which was sponsored by House Speaker R. Clayton Mitchell Jr. (D-Kent) on behalf of Gov. William Donald Schaefer.

However, today's vote followed months of intense debate over the value of the emissions tests and the best way to conduct them. Mindful of the program's impending expiration, Schaefer created a task force last year to examine how the program should be run.

The task force considered, among other things, whether the tests should be conducted by private gas stations -- instead of 10 state-designated sites that are run by a subsidiary of British Petroleum under state contract. The task force decided to leave the tests as they are.

The House bill essentially follows the task force's advice.

The legislation, which would take effect next January, calls for the testing of vehicles up to 20 years old -- eight years older than currently required. For the first time, tests would be required of trucks up to 26,000 pounds.

If a vehicle failed the test, the owner would be required to pay at least $75 for a tuneup -- instead of the current $50 minimum -- before becoming eligible to apply for a waiver.

The bill also would create a new, three-part check to detect tampering with emissions control devices. Inspectors would examine the catalytic converter and conduct two tests to see whether drivers were improperly using gasoline containing lead in cars intended for unleaded fuel.

The House Environmental Matters Committee, which voted last week to forward the bill to the full House, rejected an amendment that would have permitted owners whose cars failed to have them retested at gas stations.

The committee also rejected a change that would have eliminated the test's fee, which is currently $9. The state would have paid for the program, instead, by increasing the price of vehicle registration for all Maryland drivers.

The Senate Judicial Proceedings Committee today passed a different version of the vehicle emissions bill, which would spread the cost of the program throughout the state through an increase in registration fees.