Radon trapped in air filters, dehumidifier

We purchased a Frigidaire dehumidifier from Lowe's in Hagerstown, MD a few months ago. We put it downstairs in our basement to remove the moisture from the basement. Periodically we test our basement for radon using our geiger counter. We hadn't done it in awhile so we tested it yesterday and the background radiation was 35 cpm which is ok. The astonishing thing that happened is that our geiger counter gave a very high reading when we approached the Frigidaire dehumidifier. When I removed the filter that was encased in the dehumidifier, the filter itself read 515 cpm!!! We were flabbergasted. Apparently the filter was trapping radon in it and thus the high reading of alpha particles. Given that, we turned off the dehumidifier and let it sit overnight. Today, twenty four hours later, the filter was back to normal and the reading was 35 cpm. My worry is that the filter traps the radon particles in it and makes the dehumidifier a source of radiation. To the unwitting consumer who periodically removes the water bucket which is located near the filter, or spends time around the dehumidifier, it could be a source of radiation contamination. I wrote to the company and recommended they check into this matter and try and reduce the amount of radon that gets trapped in the filter. I will notify the Consumer Safety Product Agency on this matter.

UPDATE: I have added a HEPA filter to the basement which traps the radon. In addition, radon can be removed through a radon mitigation system. This would greatly lower the radon in the filter.