Lesson 6 What are the testing strategies for radon?

Lesson 6

What are the testing strategies for radon?

Slide 6-2

EPA goals

• Are timely• Are simple• Are cost effective• Protect human

health– Especially against

lung cancer

Help people make decisions about radon reduction that

Slide 6-3

Importance of reliable measurement

• Helps property owners decide whether to mitigate

• May be part of price negotiations in real estate transactions

What should I do to protect my family?

If the mitigation system on our new

home will cost $1500, will the seller reduce

the asking price?

Follow EPA protocols for reliable measurement

Slide 6-4

• Measures radon levels during brief test period

• Often used in real estate transactions

• Devices include– Charcoal canisters– Charcoal liquid

scintillation detectors– Electret ion chamber

devices (short-term E-PERMs)

– Continuous monitors

ReviewLength of test

Short-term test

91-365 days

• Provides more information about a home’s year-round average radon level

• Devices include– Alpha track devices– Electret ion chamber devices

(long-term E-PERMs)

Long-term test

2-90 days

Slide 6-5

Length of test

• Both types of test can provide accurate results

• Both types of test usually lead to same decisions about mitigation

Slide 6-6

General testing process(not related to sale of a home)

Step 1 Conduct a short-term test

Step 2 Determine what follow-up strategy is needed

Step 3 Conduct any needed follow-up test

Step 4 Examine results of all tests to determine what to advise the homeowner

Handout 6-1 summarizes this information

Slide 6-7

General testing strategies

Step 1: Assume you have conducted a short-term test

Step 2: Determine what follow-up strategy is needed

Follow-up depends on the first test result

0–under 4 pCi/L

(0–under 0.02 WL)

4–under 10 pCi/L

(0.02–under 0.05 WL)

10 pCi/L and above

(0.05 WL and above)

Slide 6-8

General testing

Advise the owner to test again in the future, especially if• An unused lower level becomes used as a living space• Structural changes are made• Changes in the HVAC system are made

If the first test result is0–under 4 pCi/L

You do not have to conduct a follow-up test now

Slide 6-9

General testing

If the first test result is 4 pCi/L or more,

conduct a follow-up test

4–under 10 pCi/L 10 pCi/L and above

Slide 6-10

General testing

If the first test result is 4 pCi/L or more but under 10 pCi/L

Conduct a follow-up short-term test or long-term test

With another short-term test, average the results of the first

and follow-up tests

With a long-term test, use the long-term results

If the average is under 4

pCi/L, advise the owner to test again in the future

If the average is 4 pCi/L or

more, advise the owner to mitigate

If the result is under 4 pCi/L,

advise the owner to test again in the

future

If the result is 4 pCi/L or

more, advise the owner to

mitigate

Slide 6-11

General testing

If the first test result is 10 pCi/L or more

Conduct a follow-up short-term test

Average the results of the first and follow-up tests

If the average is under 4 pCi/L,

advise the owner to test again in the future

If the average is 4 pCi/L or more, advise the owner to

mitigate

Slide 6-12

Example

• Step 1: Conduct a short-term test

• Step 2: Determine follow-up strategy – Test 1 = 5.4 pCi/L– Advise follow-up test – Since result is under 10

pCi/L, either short-term or long-term test OK

• Step 3: Conduct follow-up test (short-term)

• Step 4: Examine results – Test 2 = 3.8 pCi/L– Average = 4.6 pCi/L– Recommend mitigation

You are testing for Jeri, who has no plans to sell her Simsbury home

What do you advise?

What do you advise?

Slide 6-13

Example

• What if Jeri had requested a long-term test as follow-up?– Test 2 = 4.0 pCi/L

• What do you advise? – Recommend

mitigation

You are testing for Jeri, who has no plans to sell her Simsbury home

Slide 6-14

General testing strategiesSummary

First test result

0–under 4 pCi/L

4–under 10 pCi/L

10 pCi/L and above

No immediate follow-up

Follow-up with short-term or long-term test

Follow-up with short-term test

Slide 6-15

Questions?

• About strategies for tests that are not associated with real estate transactions

Slide 6-16

Testing associated with home sales

Why are there potential problems?

• Time pressure• Accidental violation

of test conditions• Possibility of

tampering

Slide 6-17

Testing associated with home sales

Short-term options usually preferred because of time factor

• Passive tests– Two simultaneous tests

(two tests at the same time in the same place)

– Two sequential tests (one test right after another in

the same place)

• Active test– One continuous monitor

Handout 6-2 summarizes this information

Slide 6-18

Real estate option 1Two simultaneous tests

1. Use two identical devices and methods

2. Test in same location– Place two devices 4 inches apart

3. Run tests for at least 48 hours4. Return devices to lab promptly

March 2010

5

6 Begin Tests 1 and 2

78 End Tests 1

and 2

9

Conduct two short-term tests at the same time

Slide 6-19

Simultaneous test results

Both results are under 4 pCi/L

Average will be under 4 pCi/L

Report both results and averageRecommend future retesting

Both results are 4 pCi/L or more

Average will be 4 pCi/L or more

Report both results and averageRecommend mitigation

Expect some variation between any two results

Slide 6-20

Simultaneous test resultsSpecial situation

One result is under 4 pCi/L and one result is 4 pCi/L or more

Average may be under, at, or over 4 pCi/L

Consider the difference between the two results

Slide 6-21

Simultaneous test resultsSpecial situation

One result is under 4 pCi/L and one result is 4 pCi/L or more

Consider the difference between the two results

L = lower result H = higher result Multiply L by 2 and compare with H

If H is less than L x 2, the difference is acceptable• Report results and average• If average is under 4 pCi/L, recommend future retesting • If average is 4 pCi/L or more, recommend mitigation

If H is greater than or equal to L x 2, the difference is too large• Report that the results do not agree• Retest

See handout 6-3

Slide 6-22

Simultaneous test resultsSpecial situation example

L = lower result H = higher result

Example 1: L = 3.2 H = 4.2

L x 2 = 6.4H (4.2) is less than L x 2 (6.4), so the difference is acceptable

Report results and average (3.7)

Example 2:L = 2.2 H = 4.6

Slide 6-23

Simultaneous test resultsSpecial situation example

L = lower result H = higher result

Example 1: L = 3.2 H = 4.2

L x 2 = 6.4H (4.2) is less than L x 2 (6.4), so the difference is acceptable

Report results and average (3.7)

Example 2:L = 2.2 H = 4.6

L x 2 = 4.4H (4.6) is greater than L x 2 (4.4),

so the difference is too largeReport disagreement of results (but not results) and retest

Slide 6-24

Simultaneous test resultsSummary

Expect some difference between the two results

Both results are under 4 pCi/L

One result is under 4 pCi/L and one result is

4 pCi/L or more

Both results are 4 pCi/L or more

Average will be under 4 pCi/L

If the higher result is twice the lower result or more, retestIf the higher result is less than twice the lower, report both results and averageRecommend retesting or mitigation based on average

Average will be 4 pCi/L or more

Report both results and averageRecommend future retesting

Report both results and averageRecommend mitigation

Slide 6-25

Real estate option 2Two sequential tests

First test• Run the first test for at

least 48 hours• Return the device to the

lab promptly• Immediately after the

first test is finished, run a follow-up test

March 2010

5

6 Begin Test 1

7

8

9

Conduct one short-term test after another

Slide 6-26

Real estate option 2Two sequential tests

Follow-up test• Begin immediately after first test• Use identical device and method• Use same units (pCi/L or WL)• Place device in same location• Run follow-up test for same

period as first test – Up to 2 hours difference allowed– Run for at least 48 hours

• Return device to lab promptly

March 2010

5

6 Begin Test 1

7

8 End Test 1Begin Test 2

9

Slide 6-27

Sequential testsVariation in results

Expect some variation between any two results

• Radon levels vary from day to day– Moderate variation is acceptable

• If variation is large, consider possible causes

– Weather– Air pressure– Season– Accidental disturbance of device – Opening of doors or windows – Tampering– Lab error

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

1/5 1/6 1/7 1/8 1/9

0

1

2

3

4

5

6

1/5 1/6 1/7 1/8 1/9

Moderate variation

Large variation

Slide 6-28

Sequential testsReporting results

What to report– Report both results– Use average of two test results to

determine need for mitigation

When to report– After second test to discourage

tampering• Especially if first test result is 4 pCi/L or

more

Slide 6-29

Activity

See scenario in handout 6-4• What did Hector do wrong?• Revise the scenario so that

Hector conducts the tests properly

• Consider factors that might explain differences in test results

Hector, an inexperienced inspector, ran two sequential short-term tests in a home for sale in Columbia

Slide 6-30

Questions?

• About simultaneous tests in real estate transactions?

• About sequential tests in real estate transactions?

Slide 6-31

Real estate option 3One continuous test

• Use any NEHA- or NRSB-listed continuous monitor or working-level monitor

• Use monitor that integrates and records at least every hour

Slide 6-32

Real estate option 3One continuous test

Run test for at least 48 hours• Requires about 4 hours for conditions to

stabilize– Discard data from these 4 hours or correct

them

• Must have at least 44 continuous (uninterrupted) hours of data for valid average– If you remove any data within that period (for

example, if severe weather occurs), results will not be valid

Slide 6-33

Real estate option 3One continuous test

Results0–under 4 pCi/L

4 pCi/L or more

Recommend future

retesting

Recommend mitigation

Slide 6-34

Questions?

• About continuous testing?

Slide 6-35

Summary

• Testing period– Short-term (2-90

days)– Long-term (91-365

days)– Both provide

accurate results

• Testing strategies– General testing– Testing associated

with real estate transactions

Slide 6-36

SummaryGeneral testing steps

1. Conduct short-term test2. Determine what follow-up strategy is needed,

depending on first result 0 to under 4 pCi/L 4 to under 10 pCi/L 10 pCi/L or above

3. Conduct any required follow-up4. Examine results to determine what to advise

homeowner When result is under 4 pCi/L, advise future follow-

up, especially if major changes are made When final result is 4 pCi/L or more, advise

mitigation

Slide 6-37

SummaryReal estate options

1. Two simultaneous tests using passive devices

2. Two sequential tests using passive devices

3. One continuous test

Slide 6-38

Questions?

Slide 6-39

Check your understanding

• See handout 6-5