Radon is a natu­rally occur­ring radioac­tive natural gas. You can’t see it, smell it or taste it. Never­the­less — or exactly for this reason — the element is extremely hazardous. A common cause of lung cancer (second only to smoking), this result of radium decay is respon­sible every year for 20,000 deaths in the US, about 15.000 in the EU and approx­i­mately 500 in Sweden.

The archive of the library was a taboo zone for a long time. Access was forbidden due to the high radon levels.

But radon occurs natu­rally in many types of soils. The gas becomes a hazard as soon as it pene­trates the build­ings foun­da­tions and enters the build­ings. It becomes concen­trated in indoor air and quickly achieves danger­ously unhealthy levels — which is what happed in the Stock­holm City Library. A legally proscribed energy check revealed that the radon concen­tra­tion in the building’s archive was 2,000 Bequerel per m3. The legal limit value in Sweden is 200 Bequerel per m3.

The last chance

The library imme­di­ately declared the archive in the base­ment a taboo zone. The librar­ians were prohib­ited access to thou­sands of books. While seeking a solu­tion to the problem, the library manage­ment collab­o­rated with various service providers. One company sealed all the cracks and seams in the base­ment and another tried to slightly over-pres­surize the air throughout the library. None of these measures were successful.

Through a trade fair contact, the library found Radonkon­sult, a company that has special­ized in protec­tion against radon for decades. Michael Myntelius, COO at Radonkon­sult, says: “After several failed attempts, the library manage­ment could no longer afford to exper­i­ment. This is why it was clear from the very begin­ning that we had exactly one chance to apply a viable solu­tion.”

Tiny holes, major impact

The solu­tion in place extracts the radon directly from the ground and lets the gas escape from the building through conduits.

After making exten­sive on-site measure­ments, it became apparent that Radonkon­sult would be able to apply a process in the library that had already miti­gated the problem in over 7,000 projects. To prevent radon from flowing into the room and expanding there, it must be extracted directly from the soil. Radonkon­sult drilled tiny holes with 16-mm diam­e­ters in the building’s foun­da­tion and used piping to connect them to a special radon pump. The pump contains several centrifugal blowers from ebm-papst that create a vacuum under­neath the foun­da­tion. The pump siphons off the radon before it can enter the room. Next, the gas escapes from the building through conduits, mixes with the fresh air and is rendered harm­less to humans.

The fight against radon is not an easy one – it requires plenty of know-how.

Jan Edlinger, sales engi­neer at ebm-papst in Sweden

When asked why he uses blowers from ebm-papst in the system, Myntelius answered: “One word: quality. We have already built these systems with fans from China and with prod­ucts from the Swedish compe­ti­tion. They simply cannot compare to the quality and dura­bility of the ebm-papst prod­ucts. In some systems, they have been running for over 20 years.” In the library, Radonkon­sult installed four radon pumps with seven blowers each. The result: The radon concen­tra­tion dropped from 2,000 Bequerel per m3 to 50 Bequerel per m3 within a very short time. “The fight against radon is not an easy one — it requires plenty of know-how,” said Jan Edlinger, a sales engi­neer at ebm-papst. “It is wonderful to see Radonkonsult’s results.”

In order to be certain that the low radon level was not a short-term effect, the library decided to have the base­ment moni­tored for two months before they opened it up again. The measure­ments showed that the system was consis­tently keeping the values below the limit. The librar­ians were able to return to their books and work without risk to their health.