Professional Radon Testing: What You Should Know

Although you can't see or smell radon — it can cause some serious damage to your health if left unchecked. That's why it's so important to conduct radon testing in your home, preferably before you even move in. Radon is a trace element in the atmosphere, so it's everywhere, but it also bubbles up out of the ground, and if conditions are right, it can reach toxic levels in the home. Radon is the second leading cause of lung cancer and is responsible for upward of 20,000 deaths per year, which is more than the deaths caused by falls in the home, drownings and home fires combined.

To find out if you're at risk of health complications from radon, you should test your radon levels — and you can do this yourself or have it done by a professional radon testing company. Professional radon testing is more thorough and accurate than homeowners can achieve using DIY radon test kits, but it isn't always necessary. To make the decision, it helps to know what's involved with radon testing.

Radon is a radioactive gas produced from the decay of uranium and other heavy radioactive metals in the earth's crust. This is a natural process that happens everywhere, although there are places in which it occurs to a larger degree than others. The EPA has divided the country into zones based on the prevalence of ground emissions of radon gas, but being in a zone of low prevalence isn't a guarantee of safety because pockets of radioactive decay are everywhere. A particular home can be vulnerable just because it sits on porous soil or fissured rock that provides a pathway for the radioactive gas to reach the surface.

In the United States, the EPA monitors radon emissions, and it defines 4 pCi/L as a safe upper limit for radon concentration in a home. The unit it uses, the picoCurie per liter (pCi/L), is based on the curie, a unit named after Marie Curie, the scientist who discovered radium. A curie is the radiation emitted by a gram of radium, and a picoCurie is one trillionth of a curie. That sounds small, but it's dangerous. The National Academy of Sciences reports that 800 people die every year from lung cancer contracted by breathing outdoor air where the average radon level is only 0.4 pCi/L.

The safest radon level is zero, but that doesn't exist, so we have to settle for the average outdoor level of 0.4 pCi/L, which Congress established as the safe indoor level of radon gas in the Radon Act 51. Unfortunately, two-thirds of American homes exceed that level, and in light of that reality, the EPA considers an indoor level below 2.7 pCi/L to be safe, a level between 2. 7 and 4 pCi/L to be cause for concern and a level exceeding 4 pCi/L to be actionable.

The EPA recommends that homeowners do their own self-testing using one of a number of testing kits that are readily available from hardware stores or online suppliers. Testing involves leaving a sensor, which could be a charcoal canister or an alpha track test strip, exposed to the air in the room — with the windows and doors closed — for a predetermined period. In a short-term test, you leave the sensor exposed for two to 90 days, and in a long-term test, you leave it for more than 90 days. After the testing period is over, you bag the sensor and send it to a lab for analysis.

There are a few problems with DIY testing:

• Homeowners don't always place sensors in parts of the room that are most representative of the ambient air quality. They may put sensors in corners, behind sofas or in crawl spaces where they can't take accurate readings.

• It's often difficult to control the environment in which the test is being conducted, and that's crucial. If someone opens a window or leaves a door open during the test, the test results won't be accurate.

• It can take a long time for the lab to return the test results, which isn't ideal if you suspect elevated radon levels.

Professional testers use different, more accurate testing devices, and in most states, they must be licensed. The electret method used by most pros involves deploying a statically charged Teflon sheet. It loses a tiny amount of charge every time a radioactive particle hits it, and the tester determines the radon concentration by measuring the charge of the sheet after a predetermined period. Active testing methods involve deploying continuous radon monitors that automatically analyze the air quality for a prescribed period.

Active radon monitoring and testing devices are available to consumers for about the same cost as hiring a professional tester ($150 to $250), so the opportunity to use one isn't a reason to call a pro. However, when you hire a pro, you're also paying for the knowledge of where to put the device, how to control room conditions to get accurate results and how to interpret the test results, and that expertise comes as part of the bargain.

The EPA endorses self-test kits for homeowners wanting the check their own radon levels, but it recommends professional radon testing for real estate transactions. In such situations, the radon tester is an impartial third party, like a home inspector, and the radon test is part of the home inspection process, with the testing fees usually rolled into the closing costs. Radon testers operate independently of home inspectors, although they may be affiliated, and in most states, they have to be certified. No one wants to buy a home and later discover a radon problem, so accepting a seller's assertion that self-testing has shown low radon levels is hardly ever an option — especially not for transactions conducted in EPA-designated high-risk zones.

Besides real estate transactions, there are other circumstances that can warrant professional radon testing. One such circumstance would be when a preliminary self-test shows radon levels above 4 pCi/L. Given the cost of installing a radon remediation system — not to mention the potentially hazardous conditions that exist if the test is accurate — a second test should be conducted to be sure, but beware of conflicts of interest. Be sure to have the testing and remediation done by different contractors. A professional can do the test quicker and have results in a matter of days rather than the weeks it takes for a lab to receive samples by mail and return the results, and the test methodology will be more reliable.

On the other hand, homeowners who have no reason to believe there are elevated radon levels in the home are better off purchasing an inexpensive kit or investing in an electronic monitoring device. As long as the levels stay well below the action threshold, there's no reason to call for professional testing because the test kits and monitoring devices are accurate if you use them according to the directions. Homeowners who detect radon levels between 2.7 and 4 pCi/L, which are high but not actionable, may be able to lower the levels using simple radon reduction home improvement techniques, such as sealing floors and walls and deploying heavy plastic sheeting on the exposed ground in crawl spaces.