Clorox Co. said that the health of its chief executive, Gerald Johnston, has improved since he suffered a heart attack on March 1 of this year. Mr. Johnston joined Clorox in 1981 and was named chief executive officer in July 2003 after serving as president and chief operating officer for about 4 years. The company did not disclose a timeline for his return, and said Robert Matschullat, presiding director of the board, will continue to serve as interim chairman and chief executive....