NRPP RMP flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Radon-222 half-life

Radon-222 has a half-life of about 3.82 days, decaying by alpha emission into polonium-218. This short half-life means concentrations respond quickly to changes in entry and ventilation.

Picocurie definition

One picocurie equals 0.037 becquerels, or 2.22 disintegrations per minute. U.S. radon results are conventionally reported in picocuries per liter of air.

Working Level definition

One Working Level equals 1.3 x 10^5 MeV of potential alpha energy per liter of air, corresponding to 100 pCi/L of radon at 50 percent equilibrium with its progeny.

Equilibrium ratio

The ratio of measured progeny concentration to the radon concentration that would exist at secular equilibrium. Indoor values typically range from 0.3 to 0.7 depending on ventilation and aerosol conditions.

Short-lived progeny

Polonium-218, lead-214, bismuth-214, and polonium-214 are the short-lived radon progeny. They attach to aerosols and deliver most of the radiation dose to lung tissue.

Secular equilibrium time

Radon and its progeny approach secular equilibrium after roughly 3 to 4 hours in a closed space, about seven half-lives of the 3.82-day radon parent.

Thoron distinction

Radon-220, called thoron, has a 55-second half-life and usually decays near its source. Standard radon tests target radon-222, not thoron.

Stack effect

Warm indoor air rises and escapes through upper leaks, creating negative pressure at the base of the building that draws soil gas inward. The effect strengthens with temperature difference and height.

Driving force for entry

Pressure-driven soil gas flow, typically a few pascals, dominates radon entry. Diffusion through building materials is a much smaller contributor in most homes.

Common entry routes

Slab cracks, slab-to-wall joints, sumps, floor drains, utility penetrations, and exposed crawl space soil are the principal pathways for soil gas to enter a building.

Sub-slab depressurization

A mitigation system that uses a fan and piping to create negative pressure beneath the slab, reversing the soil-to-building gradient and venting radon above the roof.

House depressurization

Exhaust fans, combustion air demands, and negative pressure from wind or HVAC operation lower indoor pressure and increase soil gas infiltration, raising indoor radon concentrations.

Waterborne radon

Radon dissolved in well water is released into indoor air during showering, laundry, and dishwashing. It can add measurably to airborne levels in homes with high water use.

Charcoal canister test

A passive short-term device exposed for two to seven days that adsorbs radon for later laboratory analysis. Results are sensitive to humidity, temperature, and exposure timing.

Alpha-track detector

A passive device using CR-39 or similar plastic that records alpha particle tracks over three to twelve months, providing an integrated long-term radon measurement.

Electret ion chamber

A passive device that measures radon by the voltage drop on a charged electret. The difference before and after exposure is proportional to integrated radon concentration.

Continuous radon monitor

An electronic device that records hourly radon values, supports tamper detection, and is used for real estate transactions and post-mitigation verification.

Closed-house conditions

For short-term tests, exterior doors and windows remain closed and fans are off for at least 12 hours before and throughout the test, except for normal entry and exit.

Device placement rules

Place devices in the lowest livable level, 20 inches to 6 feet above the floor, away from exterior walls, drafts, and direct sunlight, and at least 3 feet from openings.

Confirmatory testing

When a first short-term result is 4 pCi/L or higher, a second short-term test or a long-term test is recommended to confirm the concentration before deciding on mitigation.

Duplicate measurement

Two devices deployed side by side at the same location to assess precision. The difference between their results indicates the measurement variability of the method.

Blank device

An unexposed or sealed device shipped and analyzed with a batch to detect contamination or spurious exposure. Blank results should be near zero.

Spike sample

A device exposed to a known radon concentration in a chamber and analyzed with a batch. Recovery of the known value verifies accuracy and calibration.

Calibration factor

A multiplier derived from chamber calibration that converts instrument or device response into a radon concentration. It must be applied to every reported result.

Control chart

A plot of QC results over time with statistical limits. Points outside the limits indicate drift or bias and trigger documented corrective action.

Proficiency testing

A program that sends blind samples of known concentration to a laboratory and compares reported values with the true value to verify analytical performance.

EPA action level

The U.S. EPA action level is 4 pCi/L. EPA also recommends considering mitigation at 2 to 4 pCi/L because no radon level is considered entirely risk-free.

ANSI/AARST standards

Consensus standards that specify procedures for radon measurement, mitigation, and real estate testing. Certified professionals are expected to follow the applicable standard.

Indoor Radon Abatement Act

A 1988 federal law that authorized EPA assistance to states for radon surveys, training, and public information, and directed studies of radon in schools.

Conflict of interest

A situation in which a tester or mitigator has a financial or personal interest in the result. Ethical practice requires disclosure and separation of testing from mitigation decisions where required.

Report contents

A radon report should state device type, exposure dates, test location, closed-house conditions, measured concentration with uncertainty, and the applicable action level.

Communicating elevated results

When a result is at or above 4 pCi/L, recommend confirmatory testing or mitigation by a qualified professional and provide state or EPA resources without promising specific health outcomes.