The answer to 'lifespan of smoke detector' is that most smoke detectors have a lifespan of 8-10 years. Smoke detectors are an essential safety device in every home, but they don't last forever. Over time, the sensors and components can become less reliable and may need to be replaced.
It's generally recommended to replace smoke detectors every 10 years, or sooner if they start to malfunction or fail to detect smoke properly. Many smoke detectors also have a built-in expiration date or 'end of life' indicator that will let you know when it's time to replace the unit.