If you are deciding whether to test for radon in a St. Charles home, the first choice is usually between a short-term test and a long-term test. Both measure radon gas in the air of your home. Radon is a naturally occurring radioactive gas that comes up from soil and rock, and it can collect in basements, crawl spaces, and lower floors. It has no smell, color, or taste, so a test is the only way to know what is in your air.
Why St. Charles homes are worth a look
St. Charles sits in St. Charles County, Missouri, where public water reports describe a mix of river water and groundwater supply. Homes on private wells often draw from the Missouri River alluvial aquifer, which is a groundwater source. Groundwater can carry dissolved radon, and when that water runs through a faucet, shower, or washing machine, some of the gas can be released into the air inside the house. How much depends on the water source and how the water is used, so it makes sense to ask where your water comes from before you decide what to test.
Short-term tests
A short-term test is a practical starting point. It runs for a few days, is usually placed in the lowest livable level of the home, and gives a snapshot of conditions during that window. Keep windows and exterior doors closed as much as normal daily life allows during the test, and place the device away from drafts, supply vents, and damp spots. Weather can change results from one week to the next, so a result that comes back higher than you expected should be followed up rather than ignored.
Long-term tests
A long-term test runs for much longer, often through a season or more, and averages conditions over time. Many homeowners choose it when they want a more representative picture of normal living, especially in winter when houses are closed up and ventilation is lower. The tradeoff is time. If you are buying or selling a house, or you need an answer quickly, a short-term test may be the better first step, with a long-term test to confirm the picture.
Choosing between them
- Use a short-term test if you want a quick first reading.
- Use a long-term test if you want an average across normal seasons.
- Test the lowest occupied level, where people spend the most time.
- Follow the kit instructions exactly, including sealing and placement steps.
- Write the start date, end date, and room on the kit so the lab report makes sense later.
If your home uses a private well
Well owners should consider testing the water as well as the air. Radon in water is measured by a separate lab test, and a water sample can also be used to check other items such as nitrate, coliform bacteria, iron, manganese, and metals. Ask a state-certified or accredited laboratory which tests they offer and how to collect the sample correctly. Keep the bottle cool and deliver it promptly if the lab asks for that.
Test results from water and air answer different questions. A water result tells you what is in the supply, while an air result tells you what is in the house. If both are part of your plan, read them together, because a water source that carries radon may also be the reason a basement or laundry area shows higher readings.
What to do with the result
A test result tells you where you stand, not what caused it. If the reading is higher than you expected, the next step is usually a qualified assessment of the house, which may look at foundation openings, sump pits, floor cracks, and ventilation. Keep a copy of every report and consider retesting after major changes to the home, the heating or cooling system, or the water supply. Any decision about repairs should rest on the review of a qualified professional rather than on a single reading.