During Cosmos S.1 Ep.7, I've learned about the event of lead poisoning around the world. This episode is about a scientist named Clare Patterson, whom discovered Earth's real age. Patterson performs an experiment called "The Clean Room" where Patterson studies tiny zircon crystals. He measures the lead and it is six times more than what was in the zircons. Then something serious occurred. Patterson's lead measurement numbers were inconsistent. He thought maybe that his lab had been contaminated. Patterson did everything he could to cleanse the lab of lead. He still had 100 times too much lead. He built the first ultra-clean room. He was finally able to measure how much lead was in a rock. Humans used lead as long ago as 5000 BC, as it was able
