The most commonly used smoke detector in homes utilizes ionization technology to sense the presence of a fire in the home. This type of smoke detector represents about 95% of the smoke detector market. The reason that should concern you is because this type of smoke detector is very poor at actually detecting smoke, which it turns out is the most common killer in house fires.
On January 15, 2015 the Minnesota State Fire Marshal's office issued its annual report disclosing that 41 people died in house fires in Minnesota in 2014. Of those 41 deaths it is safe to assume that the vast majority were from smoke inhalation.
Smoke alarm manufacturers have known for decades that ionization smoke alarms are very poor at detecting smoke, and that many house fires now are of the type where smoke, not flame, is the predominant indicator of a fire. This is because most house furniture, carpeting, draperies, etc. (the kind of stuff that burns) is made of synthetic materials such as polyurethane, which is an oil-based product that gives off huge amounts of smoke, carbon monoxide and hydrogen cyanide when it burns. It does not burst into flame as quickly as older home furnishings which were mainly made of cotton or similar natural materials.
In litigation, smoke detector manufacturer's representatives have testified that ionization smoke detectors will take 30 minutes or longer to sound once a smoldering fire has started. 30 minutes is enough to kill everyone in the house.
The other type of smoke detector is one which operates on photoelectric sensing technology. In order to provide the best protection for you and your family you should consider buying and installing (and properly maintaining) both types of smoke detectors in your home.