The D.C. Zoning Commission passed an emergency ordinance yesterday that limits new adult bookstores and other sexually oriented businesses to the downtown commercial area south of Massachusetts Avenue. The vote was 4 to nothing.

The ordinance, effective immediately for 120 days, also mandates that any new sexually oriented businesses be at least 600 feet from residential and special purpose districts, churches, schools, libraries and other public buildings.

The emergency ordinance also stipulates that such businesses also must be no less than 300 feet from one another.

The 36 sexually oriented businesses already operating in the District will not be affected by the ordinance.

Ben W. Gilbert, director of the city's Municipal Planning Office, said most of those operating now are concentrated on 14th Street NW between H Street and Thomas Circle.

The emergency legislation is a stop-gap measure to prevent new businesses from operating next to residential and other areas until the National Capital Planning Commission has a chance to examine a permanent zoning regulation that would regulate such businesses, Gilbert said.

The planning commission, a federal body, has the authority under the home rule charter to reject any zoning commission action that might have a negative impact on federal property.

"Under the new ordinance, there will be a limited number of sites that would be legally available for sexually oriented businesses and even less sites for that would be offered to those who might want to operate such businesses," Gilbert said.

In May, the commission passed an emergency order, which expired today, that approved new sexually oriented businesses only on a case-by-case basis until the commission could devise stricter laws.

That earlier emergency order was prompted by protests from Georgetown residents and merchants who were irate over an adult bookstore that opened this year at 3255 M Street NW.