We all know that smoking is bad for our health and that eating vegetables is good for it. Yet how bad and how good are they? Without a clear notion of threat and reward, it is that much harder to avoid a cigarette or to choke down a serving of broccoli. “I hate when someone tells me that something is risky,” says David Spiegelhalter, a professor of risk assessment at the University of Cambridge. “Well, compared to what?”
To answer his own question, Spiegelhalter converted reams of statistical risk tables into a simple metric: a microlife—30 minutes. If you smoke two cigarettes, you lose 30 minutes of your life (top graphic). Exercise for 20 minutes, and you gain two units of microlife. Over time bad habits accelerate your aging, and good habits slow it down (bottom graphic). “That seems to resonate with people,” Spiegelhalter says. “No one likes to get older faster.”
On supporting science journalism
If you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.
Great science journalism requires human expertise, time, effort and creativity. And it costs money. That’s why I and the journalists here at Scientific American hope you’ll join our community.
When you subscribe, you are supporting staff and freelance journalists who are passionate about telling science stories that are true, important and compelling. Our editors and reporters are often experts in their fields, which means they understand the nuances of big discoveries and can untangle the breakthroughs from the hype. With a subscription, you are also supporting rigorous fact-checking to ensure the words we publish are precise and accurate. And you’re supporting original illustrations, graphics and photos that bring you closer to an advanced laboratory, an ice sheet in Antarctica or a space mission in orbit. You’re helping us craft other types of high-quality journalism as well: Our newsletters are carefully written, edited and curated by staffers you have or will come to know and love. Our Science Quickly podcast is based on original reporting, collaboration with editors and scientists and exacting production.
Subscriptions keep this engine running so we can continue to deliver thoughtful, rigorous and independent science journalism to you. In an era of viral misinformation, this work is crucial. If you value what we do, I hope you’ll consider joining us as a subscriber
Thank you,
Jeanna Bryner, Editor in Chief, Scientific American
