Four Seasons Granite Radon Test Is Underway

[Al Gerhart]

The Four Seasons Radon test started Saturday at 12:00 pm. A CO2 test is running concurrently to track the Air Change per Hour (ACH) to determine how ventilation affects the build up of Radon. The background Radon present in the empty room (50 hour test a couple days before) was .775 pCi/L of Radon.

We made a couple of changes in the testing, neither of which will affect the outcome, just made it easier to do the test. First we added a window to the room, caulked and screwed in place, then sealed with plastic box tape. And yeah, I forgot to clean the window...

The ACH of the room could possibly change from the previous value of .03 ACH, which is about 23 cubic feet of air change per hour. This is pretty tight for a room, but condos have been reported at near these levels so this is not an unobtainable ACH. But with the CO2 test running concurrently with the Radon test, this test will have the ACH established every five minutes. So the Radon is being measured, the CO2 levels, also the relative humidity and temprature.

The second change was our method of raising the CO2 levels in the room for the ACH test. We had been using dry ice, but an eight pound block costs about $9.00 and lasts only about a day and a half in the freezer, so only one test can be done. But more importantly, it was difficult to keep from putting too much CO2 into the room, which meant that the CO2 had to decay for about 24hours before the data logger started showing the drop in CO2 due to room leakage. The meter itself is capable of measuring higher ppm levels than the Hobo data logger was capable of recording.

So we tried the small CO2 cartridges used for BB guns. Go to the far corner of the room, quickly use a hammer and sharp punch to puncture the end of the cartridges, and get the hatch closed and sealed ASAP. Using three cartridges ($1.50 worth), quickly brought the Radon room up to over 1300 ppm. High enough for the ACH test to give good data, low enough that the data logger could obtain data the same day.

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Here is the first 24 hours of data, in graph form. Double click on the small graph picture to see a larger, readable version. As you can see, the Radon is climbing steadily, up to 4.9 pcI/l. After subtracting the .775 pCi/L background Radon, there is 4.145 pCi/L of new Radon in the room.

Is the room tight? It is, but this is only one day's result and it should keep climbing for many days. Increased ventilation will slow the rise of the Radon, and if enough ventilation is present, it will prevent the rise past some point. One of the experts is going to look over the data this weekend, do some calculations, and might have some ideas on what might happen as the test progresses.

[Al Gerhart]

Here are some photographs of the equipment being used to measure the Radon, CO2, temprature, and relative humidity.

First is a closeup of one of the Femo-Tech CRMs (Continous Radon Meter) with its printer. Every hour it prints out the present Radon content, and the average Radon measured during that hour. Bill Brodhead, a Radon lab owner and respected Radon researcher loaned us the two meters for our test.

Here is a photo of both, along with the CO2 meter used to keep track of the Air Change per Hour (ACH) or how much fresh air is leaking into the room or how much air is leaking out of the room. Note the small holes covered in box tape that we used to keep track of the CO2 meter during the background tests. We added a window so we could read the tape easier and even change out tape rolls if need be.

Here is a view from outside through the new window.

[Al Gerhart]

And the Telair CO2 meter on loan from Dr. Kitto. This reading is after one CO2 cylinder was released, 855 ppm. After the test is complete, MPH1 will calculate the ACH from the drop in CO2 levels per hour. Temprature and relative humidity are also tracked by the Telair, both of which can affect the air exchange and Radon measurements.

[admin]

The Radon level is over 6 pCi/L currently, on the fourth day of the test. We had a winter storm coming in the past two days, very high winds, barometer dropping along with the temperature, all of which should cause more air exchange (ACH) and slow the Radon accumulation in the test room.

6 pCi/L is 50% over the EPA action level. The national average for Radon in homes is 1.3p Ci/L, which kills 21,000 people per year. 6pCi/L would have a death rate of over 92,000 per year.

Tomorrow we are removing the paper tape record from the printers, the meters print out the current level every hour. Will add them to the spreadsheet tomorrow night, then run a graph to see what the Radon rise looks like.

[Al Gerhart]

Here is the latest graph of the results of the Radon test. The winter storm coming in and then leaving the state increased the leakage, which messed with our nice curve in the original graph. One of the researchers, radsciguy, sent a couple of charts showing the results of some of his testing along side the theoretical curve that should occur (his two results overlaped perfectly because he is using small, nearly leakproof chambers). Our original graph matched the theoretical curve, but the latest graph shows the effect of barometric changes.

Double click on the image to go to a larger, more readable version of the graph.

We are using only one type of meter for the tests, so this result is not 100% bullet proof at this time. We hope to have different type of meters soon so we can verify the results, maybe two types.

[Al Gerhart]

Here is the latest graph from the Radon test. Fluctuations caused by a winter storm coming in and I didn't seal the window with box tape for one run. The CO2 data hasn't been calculated for this run, but we have it, might explain what was happening once the calculations are done.

[Al Gerhart]

The Radon meter is holding steady at 9.3 pCi/L. I'll pull the tape off the machine tomorrow and post the results.

[Al Gerhart]

Here is the calculations for the ACH levels during our last Radon test. Still pretty tight despite the weather being crazy.

Thanks MPH for doing all the work on this.

[Al Gerhart]

I learned something this week, not to let Radon tests run too long. It makes it nearly impossible for the Average Concentration to react to changing Radon levels using our older Femto Tech CRM. I had stopped posting the Current Concentration data from the paper tapes from the meter, thought the Average Concentration was the most accurate. After watching the data climb, but the averages lagging, a light bulb went off. Reset the machine every few days, run short tests , not long ones.

Here is the latest graph. The fairly level line is the Average Radon Concentration, the peaks are the Current Concentration, what the meter read when it printed out the results for that one hour.

Now I don't have 100% confidence in this because we had only one meter running. The results were less than predicted, the average was linear, but only one measurement left some doubt. But we recieved a loaner CRM today from Femto Teck, got it inside the test room a few minutes later and will have verification tomorrow.

We also opened up the room on Friday, did some housekeeping, cleaned out the CO2 cylinders that had been left behind, then doubled the granite square footage to 36 square feet. Closer to the average small kitchen.

Guess what, the hot spots in the first granite countertop might not be a high source of Radon. Adding the second batch of granite made the Radon skyrocket up to over 20 pCi/L in just two days, faster than the first run!

Kind of scary, 20 pCi/L is like smoking 2.5 packs a day....

Will post pictures and more data tomorrow.

[admin]

Here is the first 18hours of readings from the new CRM on loan from Femto Tech. Average concentration was 26.5 pCi/L of Radon.

Double click on the picture to see a larger readable version.