Smoke alarms have saved thousands of lives ever since they became available to the general public. They really have become a necessity as a safety tool for homes as it has been proven that with the chances of dying in a fire are half of what they would be if a home didn't have a smoke detector.  The ready availability of home smoke warning units started in the early 1970s and sales grew rapidly when the price fell due to healthy competition amongst manufacturers. 

It is estimated that nowadays around 93% of US and 85% of UK homes have at least one smoke detection unit. It  is also estimated that at least 30% of those units don't work because the batteries are dead or haven't been replaced.

Smoke alarms are purposely built to warn and protect those inside buildings from potential fire accidents. Obviously with safety paramount  the location as to where they are installed is an important consideration. The detection units should be installed in rooms and parts of houses in which people sleep or take a rest, also in or near kitchens. At least one unit for each level and it's a good idea to install in rooms where there is a lot of electrical equipment like TVs and computers.

There are 2 types of household smoke alarms, the photoelectric type and ion. The ion alarm type is more sensitive and reacts quickly to hot flaming fires. The photoelectric alarm type detects fires faster and is more likely to react to heat being generated in the kitchen when cooking. Both classes of smoke alarms provide considerably good protection and are widely used.

Smoke alarms can operate using a 9 volt battery which usually lasts for about a year. The chirping of a detector every 20 seconds signals the need for a replacement battery. Some smoke detectors can be operated using the household power source, so this means no need for the battery to be replaced as often. This kind of unit has “power on” light to mean that there is power in the smoke alarm. This type of alarm unit also has a back up battery just in case the power fails. Photoelectric and ion smoke alarms should be tested monthly as well as their batteries to ensure maximum safety.