The following were among actions taken at Tuesday's meeting of the Montgomery County Council. For more information, call 251-7900.

RADON TESTING -- The council introduced a bill that would require anyone selling old or new detached residences or town houses in Montgomery County to have them tested for the radioactive gas radon. The bill, introduced by council President Rose Crenca, would further require sellers to notify both the buyer and the county Department of Environmental Protection of the results of the radon test.

The proposal came one day after County Executive Sidney Kramer urged all property owners to voluntarily have their buildings tested to find out if corrective measures are necessary. His comments came in a letter to Crenca, accompanying a report by a county radon task force.

Radon, which is produced through the decay of uranium, moves through soil and rock and can enter a building through small cracks and openings in concrete or wall-floor joints. Health experts say that long-term exposure to the colorless, odorless gas is associated with a risk of lung cancer.

The task force based its report on 3,596 tests of county houses performed by private firms, and found that "at least some part of up to one third of all dwelling units may contain radon levels above" federally recommended guidelines.

John Menke, director of the county Department of Environmental Protection, said Crenca's bill "goes way beyond" Kramer's recommendations for testing.

Crenca's proposal directs Menke's department to establish "acceptable levels of indoor radon concentrations." Menke urged caution in proceeding with the bill because, he said, there would "enormous legal or policy implications" since no enforceable standards have been set by the federal government.

Crenca said she did not wish to "panic" county residents, and for that reason set June 1, 1988, as the date to set the provisions of the bill in motion.

In addition to the bill, Crenca introduced a resolution that would require Kramer to test all public buildings for radon and take steps to lower any unsafe levels.

DAY CARE -- The council introduced a bill by Vice President Michael Subin to allow a child care provider to receive a property tax credit of up to $2,000 if the provider makes improvements to the property used specifically for the care of the children.

Improvements started before July 1, 1987, or finished after July 1, 1991, would not be eligible under the bill.

Subin said there is a shortage of child care providers in the county and the tax credit would offer incentive for providers.

TRANSFERABLE DEVELOPMENT RIGHTS -- In a meeting Monday, the council voted unanimously to restore the controversial transferable development rights (TDR) program, which allows land developers to build more housing than zoning regulations normally allow in eight designated areas.

The TDR process, which limits owners of rural property in developing their land, but allows them to sell the development rights to that land, was ruled illegal two months ago by the Maryland Court of Appeals. The court ruled that the council acted illegally seven years ago in enacting the TDR legislation by using its planning powers rather than by passing a formal zoning change as governed by state law.

Monday's action begins the process to formally approve a new form of TDR zoning.