Richland County Health Department Prevent. Promote. Protect. According to the CDC, nearly 1 in 2 U.S. adults has hypertension, yet only 1 in 4 has it under control. Richland County Health Department Prevent . Promote . Protect . According to the CDC , nearly 1 in 2 U.S. adults has hypertension , yet only 1 in 4 has it under control .