Radon gas is found in the soil in many areas of the United States, and it enters homes by rising upwards through concrete foundations and crawlspaces. Radon gas can be hazardous to your health, as exposure to high levels of radon will increase your risk of developing lung cancer.

Since you can't see or smell radon, the only way to know if your home contains a hazardous level of radon is to use testing equipment. Like any test, however, there's a risk that you might receive a false negative if you're not using the test kit properly. To learn three ways a radon test can give you a false negative, read on.

1. Ending the Test Too Soon

One of the most common ways to receive a false negative on a home radon test is to send in your testing kit too soon. The test kits sold at home improvement stores are passive tests, which means that they naturally absorb radon from the air. The manufacturer of the kit will specify how long you need to let the kit remain in your home.

When you send the test kit to the laboratory, the lab will measure how much radon the test kit has absorbed. They'll divide the amount of absorbed radon by the number of days it was supposed to spend in your home in order to calculate your home's average radon level. If you send in the test kit too early, it won't have enough time to absorb radon. Your reading will be abnormally low, and you may receive a false negative from your radon test.

2. Placing the Test Kit Near a Window or Exterior Door

Another way that you can receive a false negative from a home radon test is to put the kit too close to a source of ventilation, like a window or exterior door. Outside air will flow in through the door or window and mix with the air near the test kit. This can dilute the levels of radon gas near the test kit, so it won't be able to absorb enough radon to provide an accurate reading. When you're using a passive test kit, you need to place the kit far away from any sources of outside air in order to avoid a false negative.

3. Testing the Wrong Rooms

The radon gas in the soil underneath your home rises upwards through your foundation, which means that radon levels are usually highest at the lowest point of your home. When you're performing a home radon level test, you need to test rooms on the ground floor. If you use your basement or crawlspace regularly, you also need to test these as well. If you don't test the rooms in your home where radon levels are highest, you may receive a false negative from the test.

Following the instructions in the test kit will minimize your chance of accidentally receiving a false negative from the test. If you're worried that you're not performing the test correctly, call a home radon-level testing service in your area. A professional radon testing service will place passive test kits in the correct locations in order to see if your home contains hazardous levels of radon gas, and they can also use active radon test equipment to get an instant reading of the radon gas levels in each part of your home. Hiring a professional for radon tests will give you more peace of mind about the radon levels in your home.