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PRO-LAB

PRO-LAB RL116

Long-term radon test kit

  • Long-term kit
  • 90 days to 12 months
  • Alpha track
  • Lab fee extra

Best for, and skip if

Best for you if

  • You want a home's average over a season or a year rather than a few days.
  • A short-term test came back at or above 4 pCi/L and you have time for the long-term follow-up the EPA describes.

Skip it if

  • You need a result within days, for example during a home sale.
  • You want to watch radon change hour by hour or week by week; this kit reports one average at the end.
See how it compares: Best radon test kits, every kit comparedWho it fits
  • PRO-LAB RL116

Photos: PRO-LAB

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  • Test length90 days to 12 months
  • MethodAlpha track
  • Lab feeExtra
  • Every figure checked against the specifications PRO-LAB publishes
  • Independent test results shown the same way for every product, unranked
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About this item

As PRO-LAB states it

  • How it measures: Alpha track detector in a sealed bag; laboratory analysis
  • Exposure time: 90 days to 12 months
  • Lab fee: Paid separately
  • Power: None needed

The PRO-LAB RL116 is a do-it-yourself long-term radon test: one passive detector that starts when you take it out of its sealed bag, stays in place for 90 days to 12 months, and goes back to PRO-LAB in Weston, Florida in a prepaid envelope, with the lab fee paid separately. The National Radon Safety Board lists a Pro-Lab alpha track detector among the devices it approves and accredits Pro-Lab Inc's laboratory to analyze it. PRO-LAB says it sends an evaluation of your home's radon level within 2 weeks of receiving the detector.

What you get

PRO-LAB's instructions describe the kit's parts: the black detector in its sealed clear bag, a long-term radon data card that you detach, keep safe during the test and send back with the detector, and an enclosed Business Reply envelope with prepaid postage for the return. The FAQ adds that the detector carries a void sticker that must stay in place. PRO-LAB's long-term page and FAQ state no warranty for the kit.

In the box and running costs

How it works

What it measures and how

The sensor, the sampling and the readings, then who has checked it

How it works

In our words, from the maker's documents

A long-term test answers a different question from a short-term one. PRO-LAB says the RL116 gives an average radon level in your home over an extended period, 3 months to 1 year, and its FAQ recommends a minimum of 90 days and a maximum of 12 months. The EPA counts any test that stays in a home for more than 90 days as long-term, and says a long-term test is more likely than a short-term test to tell you a home's year-round average, because radon levels tend to vary from day to day and season to season.

The detector is passive. PRO-LAB describes a single black detector sealed in a clear plastic bag: once it is out of the bag it is active, and there are no caps or parts to remove. Nothing runs on power and nothing shows a number while it sits in the room. PRO-LAB asks you not to remove the void sticker or try to open the device, which it says makes the sample invalid. The measurement happens at the end, when the laboratory analyzes the detector you mail back with its data card.

PRO-LAB's web pages do not name the detector technology in their text; the RL116 box PRO-LAB pictures on its radon kits page lists one long-term alpha track detector. The National Radon Safety Board's July 2026 list of approved devices includes a Pro-Lab Alpha Track detector, device 10401. The board's June 2026 list of accredited laboratories shows Pro-Lab Inc of Weston, Florida accredited until March 30, 2027 to analyze two devices: that alpha track detector and a Beckman liquid scintillation vial, the technology PRO-LAB names for its short-term detectors. The EPA names alpha track and electret ion chamber detectors as the ones commonly used for long-term testing.

PRO-LAB positions the RL116 as the follow-up to its short-term kit. It describes short-term detectors such as its model RA100 as excellent for initial screening, says radon levels can vary dramatically over a short period of time, and recommends the RL116 for more conclusive results when a first short-term result calls for a long-term follow-up. That matches the EPA's sequence: take a follow-up test after a high first result, either a long-term test or a second short-term test, and the long-term test is the one more likely to show the year-round average.

The result is one number, the average over the whole time the detector was out. The EPA's home buyer's guide says that when long-term test results are at or above 4 pCi/L, it recommends fixing the home, and its Citizen's Guide suggests considering a fix between 2 and 4 pCi/L. The EPA reads a long-term result on its own, where it averages a first and second short-term test.

PRO-LAB is the brand of Professional Laboratories, Inc. Its long-term page says its kits are sold at over 40,000 home centers, hardware stores, pharmacy chains and supermarkets, naming The Home Depot, Lowe's, Menards, Ace Hardware, True Value, Kroger, Fred Meyer, Giant Eagle and CVS among them; its where-to-buy page puts the figure at over 60,000 and adds a button to buy online. If you cannot find the kit in a store, PRO-LAB gives a phone number to buy direct. Which store stocks the long-term kit on a given day is not something PRO-LAB's pages state.

What the manufacturer says

PRO-LAB's own statements, attributed

  • PRO-LAB saysPRO-LAB states that the RL116 gives an average radon level in your home over an extended period of 3 months to 1 year.
  • PRO-LAB saysPRO-LAB's FAQ states that the RL116 is recommended for a minimum of 90 days and a maximum of 12 months, and that PRO-LAB must receive the sample within 2 months of the stop date.
  • PRO-LAB saysPRO-LAB states that it sends an easy-to-read evaluation of the exact radon gas level in your home within 2 weeks after it receives the detector.
  • PRO-LAB saysPRO-LAB states that opening the device, or removing its void sticker, voids the possibility of analysis.
  • PRO-LAB saysPRO-LAB states that all analyses are performed by PRO-LAB or by laboratories it recognizes as licensed, certified or accredited.
  • PRO-LAB saysPRO-LAB states that it is not owned by or beholden to any company selling pollution abatement services or air or water treatment devices.
  • PRO-LAB saysPRO-LAB states that New Jersey residents pay an additional fee that goes to the New Jersey Department of Environmental Protection, and that as a condition of its licensing it submits results, not client information, for the state's statistics.

These are PRO-LAB's own statements, attributed to it. They are not our findings, and we have not tested this product ourselves.

Independent evidence

Who checks a device like this

C-NRPP's consumer evaluation covers electronic monitors, not laboratory-analyzed test kits, so it has no result for PRO-LAB RL116. A kit's result comes from the laboratory that analyzes it. Where the maker names that laboratory, or the page cites the National Radon Safety Board's lists of approved devices and accredited laboratories for it, the “How it works” panel and “Questions people ask” say so.

NRSB lists
NRSB's Accredited Radon Laboratories list (June 2026) includes Pro-Lab Inc, Weston, FL, ARL0028, accredited for 10401 Pro Lab Alpha Track and 12191 Beckman Ready Rad Liquid Scintillation Vial, ARL expiration 3/30/2027; NRSB's approved device list (July 2026) includes 10401 Pro-Lab Alpha Track, method AT (alpha track). The RL116 box PRO-LAB pictures names one long-term alpha track detector. Checked October 8, 2026.

PRO-LAB RL116

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Specifications

Specifications

Every figure as the maker states it

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The maker's figures

Type
Long-term test kit, one alpha track detector, 90 days to 12 months, mail-in
How it measures
Alpha track detector in a sealed bag; laboratory analysis
Exposure time
90 days to 12 months
Lab fee
Paid separately
Power
None needed
Units
Not stated by the manufacturer

What is in the box

PRO-LAB's instructions describe the kit's parts: the black detector in its sealed clear bag, a long-term radon data card that you detach, keep safe during the test and send back with the detector, and an enclosed Business Reply envelope with prepaid postage for the return. The FAQ adds that the detector carries a void sticker that must stay in place. PRO-LAB's long-term page and FAQ state no warranty for the kit.

Keep the envelope with the card. PRO-LAB's FAQ says it does not send replacements for lost or misplaced prepaid mailers; without one, you can send the detector to the address on the information form or to PRO-LAB's physical address in Weston, Florida.

What it costs to run

The lab fee is separate. PRO-LAB's radon kits page lists the RL116 apart from a long-term kit it labels Lab Analysis Included, SKU RL416, and the RL116 box PRO-LAB pictures says a lab fee is required. PRO-LAB's long-term instructions state no lab-fee amount, and the box pictures carry their own figures, so check the current fee with PRO-LAB before you buy.

New Jersey residents pay an extra state fee. PRO-LAB's long-term instructions ask them to send a check made payable to PRO-LAB for the New Jersey Department of Environmental Protection's administrative costs, and its FAQ says the fee is required for all samples collected in the state.

Return postage is prepaid through the Business Reply envelope, and PRO-LAB does not replace a lost mailer. There are no batteries, apps or subscriptions; the cost is one kit and its lab fee per test, and a long-term test ties up that one detector for at least 90 days.

Fit and setup

Who it fits, and how to use it

The fit, then setup and placement as the guidance asks

Who it fits

Good fit if, and look elsewhere if

Good fit if

  • You want a home's average over a season or a year rather than a few days.
  • A short-term test came back at or above 4 pCi/L and you have time for the long-term follow-up the EPA describes.
  • You can leave one detector undisturbed for at least 90 days and mail it back as soon as the test ends.
  • You want a laboratory result without buying or powering an electronic monitor.

Look elsewhere if

  • You need a result within days, for example during a home sale.
  • You want to watch radon change hour by hour or week by week; this kit reports one average at the end.
  • You are likely to move, open or disturb the detector before 90 days are up.
  • You want the lab fee inside the kit price; PRO-LAB sells that as a separate long-term kit, the RL416.

Setup and placement

7 steps

  1. PRO-LAB's instructions, following the EPA, put the test in the lowest lived-in area of the home that is regularly used for 8 to 10 hours a day, in a room where the detector is not exposed to drafts from vents, doors or windows. They rule out a kitchen, bathroom, crawl space, furnace room, closet or laundry room, and any spot in direct sunlight or near a heat source such as a fireplace or heater.
  2. PRO-LAB's FAQ draws the line a little differently: it recommends testing the lowest floor, whether basement, first or second floor, where someone in the household spends 6 or more hours a day, 7 days a week. The instructions say 8 to 10 hours a day. Both point to the lowest floor your household actually lives on, rather than an unused basement.
  3. Take the detector out of its bag only when you are ready, because the test begins the moment you do. Hang or place it at least three feet from exterior doors or windows and at least two feet off the floor, then leave it in place and undisturbed for the whole test. Do not open the device or peel off its void sticker.
  4. Record the detector's serial number, the test location and the start date on the long-term data card, then detach the card and keep it somewhere safe: PRO-LAB says you need it to complete the test. When the test ends, add the end date and the rest of the details, such as your name and address, since PRO-LAB says a detector sent with missing information cannot be analyzed.
  5. Then put the detector and the data card into the enclosed Business Reply envelope, which has prepaid postage. PRO-LAB's long-term instructions say to mail it within 24 hours of the end of the test, while its FAQ says PRO-LAB must receive the sample within 2 months of the stop date. The two do not say the same thing; mailing at once meets both.
  6. PRO-LAB's FAQ says registering the kit online is a fast way to see results online but is not required, and that reports are emailed or mailed when the analysis is complete either way. If you put an email address on the form, it says a confirmation is sent when the sample arrives.
  7. The EPA's general guidance points the same way as PRO-LAB's: the lowest lived-in level, a room used regularly but not the kitchen or bathroom, at least 20 inches above the floor and away from drafts, high heat, high humidity and exterior walls.

For where any radon test or monitor should sit in a home, see where to place a radon test.

Compare

Compare with similar items

The same three rows for each, and the one difference that matters

Compare side by side

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All long-term test kits

Questions

Questions people ask

6 questions about the PRO-LAB RL116, answered

Asked about the RL116

How long does the PRO-LAB RL116 long-term radon test take?

PRO-LAB's FAQ gives the RL116 a minimum of 90 days and a maximum of 12 months in place; its instructions say three to twelve months. After the test ends, mail the detector right away: PRO-LAB must receive it within 2 months of the stop date, and it says it sends the evaluation within 2 weeks of receiving it.

Is the lab fee included with the RL116?

No. PRO-LAB lists the RL116 separately from its long-term kit with lab analysis included, the RL416, and its long-term instructions state no fee amount, while the box pictures carry their own figures, so check the current fee with PRO-LAB. Return postage is prepaid. New Jersey residents also send PRO-LAB a check for a state fee.

What kind of detector is in the PRO-LAB long-term kit?

A passive alpha track detector, by PRO-LAB's box and the National Radon Safety Board's lists, which approve a Pro-Lab Alpha Track device and accredit Pro-Lab Inc's laboratory to analyze it. The EPA names alpha track and electret ion chamber detectors as the ones commonly used for long-term tests. PRO-LAB's FAQ describes a single device that becomes active once it is out of its sealed bag, with no caps or parts to remove.

Do PRO-LAB's own pages agree on the details?

Not entirely. The long-term instructions say to mail the detector within 24 hours of the end of the test, while the FAQ says PRO-LAB must receive it within 2 months of the stop date. The instructions ask for a room used 8 to 10 hours a day, while the FAQ recommends the lowest floor where someone spends 6 or more hours a day.

The store count differs too: over 40,000 outlets on the long-term page, over 60,000 on the where-to-buy page. None of these changes how to run the test: open the bag when the detector is in place, leave it for at least 90 days and mail it promptly.

The box pictures on PRO-LAB's own pages also differ from its text. The box on the long-term page says email or text result notifications come within 1 week, against the 2 weeks in the instructions, and the box on the radon kits page gives a different New Jersey fee from the instructions. Ask PRO-LAB which applies before you mail the detector.

Should I use a long-term or a short-term test?

A short-term test is the quickest way to screen a home. A long-term test, more than 90 days, is more likely to tell you the year-round average. The EPA suggests a follow-up when a first short-term result is at or above 4 pCi/L, with a long-term test as one of its two options, and its home buyer's guide says long-term tests can confirm initial short-term results when time permits. Our short-term vs long-term guide sets the choice out side by side.

Is the PRO-LAB RL116 sold at Home Depot or Lowe's?

PRO-LAB names The Home Depot, Lowe's and Menards among the stores that carry its test kits, and gives a phone number to buy direct if you cannot find one. Its pages do not list which stores stock the long-term kit at any moment, so match the model number RL116 on the box.

What to do next

Updated October 8, 2026