Gov. Jack Markell signed the ban on smoking e-cigarettes in indoor public areas in a ceremony Tuesday at a Wilmington restaurant. The legislation adds electronic cigarettes to Delaware's existing prohibition on smoking in restaurants, bars and other public places. The new law contains an exemption for businesses that sell electronic cigarettes if 80 percent of revenue comes from such products and the business meets certain other conditions. Electronic cigarettes, which do not contain tobacco and are not regulated by the Food and Drug Administration, heat liquid nicotine into an inhalable vapor. The chief sponsor of the legislation says e-cigarette emissions contain nicotine and other harmful chemicals, including chromium and nickel.