The number of Americans aware of their cholesterol level has more than tripled between 1987 and 1989, indicating education programs about the artery-clogging substance's health dangers are working, researchers said.

However, certain groups, including the poor, smokers, young adults and the lazy need more prodding, the federal Centers for Disease Control said Thursday in its Morbidity and Mortality Weekly Report.The median proportion of people over 18 who knew the level of cholesterol in their blood jumped from 6 percent in 1987 to 21 percent in 1989, the CDC said.

The proportion of adults whose cholesterol level was checked during the same two-year span rose from 47 percent to 56 percent.

The percentage who had their cholesterol checked in 1989 ranged from a low of 48 percent in Alabama and New Mexico to a high of 64 percent in Connecticut, the CDC said in its survey of 39 states and the District of Columbia.

The percentage who knew their cholesterol level ranged from 12 percent in the District of Columbia to 33 percent in Washington state.

The National Cholesterol Education Program recommends that people 18 and older have their cholesterol level measured at least once every five years and take steps to lower the level if it reaches the danger zone.