Keeping the blood supply adequate begins with changing the way people think about blood. It is more than a medical remedy; it is also 4 a substance that has scientific, political, financial, and social implications. Because it is one of this country’s more precious human resources, it is, in fact, red gold — the name of a four-part PBS documentary about blood. Scheduled for Sunday nights, June 23 and June 30, the series is sponsored by Chiron and Ortho-Clinical Diagnostics. The American Red Cross, the American Association of Blood Banks, and America’s Blood Centers are joining forces with these companies to encourage audiences to view the four-part Red Gold PBS documentary. See local listing for air times in your location.