1. What are the units for measuring radon?
Lesson 4
What are the units for measuring radon?

2. Radioactivity units Picocuries (pCi)
Measures
Activity (radioactive decays/second)
1 picocurie (pCi)
= decays/second
= 1 decay/27 seconds
= 2.22 decays/minute

3. Radon units Picocuries/Liter (pCi/L)
Measures
Activity (decays/minute) per volume (one liter of air)
1 pCi/L
= 2.22 decays per minute per liter of air

4. EPA action level Picocuries/liter
4 pCi/L
= 4 x 2.22 decays/minute/liter
= 8.88 decays/minute/liter

5. International System (SI) Radioactivity units
1 becquerel (Bq)
= 1 decay/second
= 27 pCi
1 pCi
= decays/second
= Bq
Henri Becquerel, discovered radioactivity in 1896

6. International System (SI) Radon units
1 pCi/L
= 37 Bq/m3

7. EPA action level International System (SI)
4 pCi/L
= 4 x 37 Bq/m3
= 148 Bq/m3

8. Measuring radon decay products (RDPs)
Measure alpha radiation emitted by short-lived RDPs
Polonium-218
Lead-214
Bismuth-214
Polonium-214

9. Measuring RDPs Working level (WL)
= Concentration of RDPs produced from one liter of air that contains 100 pCi/L of radon
= Amount of short-lived RDPs that exists at a single moment if a container is kept at a constant 100 pCi/L

10. Working level EPA action level
4 pCi/L
= 0.02 WL

11. EPA action level Summary
4 pCi/L
148 Bq/m3
0.02 WL

12. Questions?

13. Characteristics of radon decay products (RDPs)
Solid particles
Electrically charged
React chemically

14. Factors that affect radon and RDP concentrations
Air circulation
Air moving within a room
Ventilation
Fresh air entering a room
Air filters
Particles suspended in the air
Dust
Smoke
Aerosols
Some RDPs plated out

15. Secular (eventual) equilibrium
Takes 3-4 hours
At secular equilibrium,
1 WL = 100 pCi/L
Radon decay products 
Radon
Radon

16. A home inspector’s lament and pledge
Picocuries and becquerels; secular equilibrium.
Radon decaying has made my brain cells go numb.
But I do understand: breathing radon’s not healthy,
So I’ll master these concepts, though they won’t make me wealthy.
Convert all these measurements? Curse that uranium!
I’m working at levels that hurt my poor cranium.
This slide is intended as a little light relief and as a reminder of why this information is important. Read it aloud.
Practice beforehand to get the rhythm, which is a bit tricky. And the rhymes are not perfect.
I’ll learn proper techniques, use the right protocol,
To help prevent cancer: that’s the goal of my role.

17. Summary EPA action level
4 pCi/L = 148 Bq/m3 = 0.02 WL
4 4 pCi/L = 148 Bq/m3 = 0.02 WL

18. Summary Factors affecting measurement
Air circulation
Ventilation
Air filters
Particles in the air
Importance
Factors affect conditions for testing a home