OWNERS of older one- and two-family houses in New York City, aware that asbestos is lurking somewhere in their homes, will have to face some difficult decisions as a consequence of new city regulations.

Asbestos is an insulating material used mainly to wrap pipes and provide a fire-retardant shield for a boiler. Around 1980, when its carcinogenic potential became widely recognized, its use was discontinued. Even so, it was only last year that city agencies begun promulgating the formal regulations that now tightly control its handling and disposal, adding onto state and Federal requirements already in force.

Homeowners most likely to be directly affected, according to asbestos removal contractors and city officials, are those whose houses and heating systems are more than 40 years old. Many still have the original boilers, designed for coal and later converted to oil or natural gas. It was common to wrap them in asbestos. The heating pipes, too, were wrapped, although usually the exposed asbestos was confined to the basement area.