5 Alarms You Must Have In Your Home First Alert You probably already have smoke detectors in your home (if you don't, stop reading this article right now and go out and buy some). But while a smoke detector can keep you safe from fire, other deadly dangers lurk in the home and many people don't have the equipment necessary to sound the alarm. So to supplement your smoke detector and make your home a safer place, here are five alarms to warn you of potential household threats. Radon Killing as many as 20,000 people a year, radon is second only to smoking as a cause of lung cancer, and the leading cause among non-smokers. This colorless, odorless gas results when naturally occurring uranium in the soil decays. Without proper prevention, this gas can become trapped in the home, a problem that plagues one in 15 homes, according to the Environmental Protection Agency. Fortunately, a single-use radon test costs less than $15 and a radon detector that provides constant monitoring can be had for about $130. If a test does come back showing elevated radon levels, don't panic. A licensed contractor can find and seal up any entry points and install a vent system to expel the gas. Carbon Monoxide A byproduct of burning fossil fuels, carbon monoxide can build up from things around the house such as a generator, a poorly maintained heating system, a barbecue or a car left running in the garage. Every year, more than 400 people die from this odorless, colorless gas, and even a non-lethal dose - which hospitalizes 4,000 people each year - can leave you feeling seriously ill, causing symptoms like dizziness, nausea, vomiting and chest pains. Carbon monoxide is one of the most common household threats, and 25 states have laws on the books requiring the detectors in certain residential buildings. So there's a good chance that you already have a carbon monoxide alarm in your home. If you don't, detectors start under $20, which is a small price to pay for peace of mind. Radiation In the wake of Japan's catastrophic earthquake and ensuing nuclear meltdown, makers of radiation detectors in this country have been seeing record sales, as Americans look to protect themselves from the possibility of a similar disaster here. Radiation often occurs naturally, yet poses little problem for humans - a granite countertop, for instance, can give off low levels of radiation. However, at higher concentrations, radiation can be extremely deadly, and it is often the manmade sources of radiation that pose the biggest threat - for instance the radiation released from power plants or x-ray machines in hospitals. Because these sources of radiation are carefully controlled and regulated to prevent human exposure, you're not very likely to encounter a deadly dose. However, as nuclear disasters in Fukushima and Chernobyl have shown, the potential is there for a catastrophic occurrence, and some people, particularly those living near a nuclear power plant, may wish to arm themselves with a home radiation alarm. Fortunately, there are many to choose from, including one that links up to an iPhone, and another that will email you when it detects heightened levels of radiation. Natural Gas Natural gas is the most common source of heat in the U.S. and is also used to power water heaters, clothes dryers and ovens. In the wild, natural gas is odorless, but the stuff that gets pumped into our homes has an odorant added to it, giving it its distinctive rotten egg smell. So in the case of a potential gas leak, your single best detector is your own nose. You can supplement your power of smell with a natural gas alarm, many of which will also test for propane and carbon monoxide. Gas leaks are rare, but they can set off catastrophic explosions, so if your alarm does go off and you smell gas, it is best to leave the home and call the fire department immediately. Propane Propane is heavier than air, so a leak could potentially fill up a room, creating both a risk of asphyxiation or explosion. For most people, the tank for a gas grill is the only time they might come into contact with propane, and this tank alone doesn't pose much of a risk since it is usually kept outside or in a garage. However, many RVs and trailers are propane-fueled, so if you have one of these vehicles, it's a good idea to install propane detectors inside. Additionally, people that rely on a propane generator or an indoor propane heater should also invest in one of these alarms. Fortunately, most propane detectors will also alarm you to the presence of natural gas, so make sure to get a detector that can handle both to save yourself a little money.