After highly publicized emergencies such as bombings or natural disasters is the time when most people think to donate blood, because they want to help. Blood is considered unusable 6 weeks after being collected and is discarded. (https://www.redcrossblood.org) Even blood that is only 2-3 weeks old leads to nearly a 50% less survival rate than blood collected within the last 10 days when given to cardiac surgery patients (https://www.hopkinsmedicine.org)
Blood doesn't last long, and most of what gets donated during highly publicized emergency situations will be thrown away, unused. Because of low inventory though, many blood banks will hold onto blood for the full 6 weeks even when it is considered less effective, until it is completely unusable.
If you are considering donating blood, don't do it because a natural disaster on the news influences you to. Donate a month after the natural disaster, when less people are thinking of donating because they all feel so good from donating and helping last month. Or donate when there hasn't been a major tragedy recently.
