Currently in India over 12 million units of blood is required annually but only nine million units is available. As in many countries including India the demand exceeds supply blood banks face the challenge of making blood available while taking care of the safety and hygiene. An adequate supply can only be assured through regular donations by voluntary unpaid blood donors. But before you plan to donate blood here are few things you need to know says Dr Nitin Agarwal Associate Consultant Blood Bank & Transfusion Medicine Jaypee Hospital Noida. #1: The minimum time gap between two successive blood donations