Smoke alarms are one of the simplest and most effective life-saving devices ever invented. Their story spans over a century of innovation, starting with industrial fire detectors and evolving into today’s compact, smart home alarms.
The first concepts for automatic fire detection date back to the late 1800s. In 1902, English inventor George Andrew Darby patented an electrical device that could detect heat and smoke, though it was large, costly, and intended for industrial settings.
A major breakthrough came in 1939 when Swiss physicist Walter Jaeger was trying to create a poison gas detector. The device failed to detect gas, but Jaeger noticed cigarette smoke disrupted the electric current inside the ionization chamber. This unexpected finding became the foundation for ionization smoke detection technology.
Throughout the 1950s and early 1960s, ionization detectors were used mainly in commercial and industrial buildings. They were expensive, bulky, and ran on AC power. That changed in 1965 when engineer Duane Pearsall and Donald Steele introduced the SmokeGard 700 — the first practical, battery-powered home smoke detector.
By the early 1970s, mass production brought prices down, and photoelectric detection technology — which detects smoldering fires — was introduced for residential use. In 1976, some U.S. states began requiring smoke alarms in homes, and public safety campaigns by the National Fire Protection Association (NFPA) pushed adoption nationwide.
By the mid-1990s, smoke alarms were required by code in most U.S. homes. Today’s models often combine ionization and photoelectric sensors, feature sealed 10-year batteries, and can wirelessly connect to other alarms or smart home systems. According to the NFPA, working smoke alarms cut the risk of dying in a home fire by about half.
From their industrial origins to their role as an everyday household necessity, smoke alarms remain one of the most important advancements in fire safety — a small device with the power to save countless lives.