PRO-LAB RL416

This is a test of averages. PRO-LAB's store page says the RL416 is used to find the average radon level in your home over a long, extended period, 3 months to 1 year, and points anyone who wants the current level to its short-term kit instead. PRO-LAB's FAQ sets the long-term kit's window at a minimum of 90 days and a maximum of twelve months. The EPA counts a test that stays in a home for more than 90 days as long-term, and because radon levels tend to vary from day to day and season to season, a long-term result is more likely than a short-term one to tell you the home's year-round average.

Nothing in the kit runs on power or shows a number. PRO-LAB's FAQ describes the long-term device as a single detector that becomes active once it is out of its sealed plastic bag, with no caps or parts to remove, and warns that peeling off the void sticker or opening the device makes the sample invalid. The long-term instructions describe a black detector in a clear bag and say the test begins the moment the bag is opened. The reading is produced later, at the laboratory, from the detector you mail back.

PRO-LAB's web text does not name the technology. The RL416 box PRO-LAB pictures on its radon kits page, printed with the number RL416, lists one long-term alpha track detector, and the National Radon Safety Board's July 2026 list of approved measurement devices includes a Pro-Lab Alpha Track, device 10401. An alpha track detector holds a special plastic or film inside a filter-covered chamber that lets radon in while filtering out its decay products; alpha particles from radon decaying in the chamber leave damage tracks in the plastic, and at the end of the test a laboratory counts the tracks. The number of tracks correlates with the integrated radon level over the whole test. The EPA names alpha track and electret ion chamber detectors as the devices commonly used for long-term testing.

PRO-LAB says all analyses are done by PRO-LAB or by laboratories it recognizes as licensed, certified or accredited. The National Radon Safety Board's June 2026 list of accredited radon laboratories includes Pro-Lab Inc of Weston, Florida, laboratory ARL0028, with the Pro Lab Alpha Track among the devices listed for it and an accreditation that runs to March 30, 2027. PRO-LAB is the brand of Professional Laboratories, Inc., the company behind those analyses.

PRO-LAB sells two long-term kits under one name. Its radon kits page lists the PRO-LAB Radon Gas Long-Term Test Kit as SKU RL116 and, separately, the PRO-LAB Radon Gas Long-Term Test Kit (Lab Analysis Included) as SKU RL416, UPC 683431994164. The long-term instructions PRO-LAB publishes sit on its long-term kit page, which names the RL116 as its model; this page follows them for the RL416 as well. Where the instructions in your box differ, follow the box.

The result is one number: the average radon level over the whole time the detector was out of its bag. The EPA's guide for home buyers and sellers 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; it averages two results only when both are short-term tests.