Prior to the 1950s, doctors thought lead poisoning was mostly a risk for industrial workers. Then, a doctor's hunch to test kids for lead revealed the issue was far more widespread than anyone had imagined.
Long-term exposure to certain kinds of air pollution increases the risk of premature death in Americans over 65 years old. And that finding holds true even at levels of air pollution below national standards.
Scientists have linked fracking with health issues for people who live near gas wells. Many wonder whether the fracking process itself is to blame. But one researcher thinks the problem might have nothing to do with fracking, but rather something we see so often, we hardly ever notice it.