At that level, I really wouldn't worry. Radon is everywhere at varying amounts and is not the only radiation source that we're exposed to, although for a lot of us, it's the biggest.
You're well below the action level and only a small amount above the target level. The target level is set as something to aim for for people who were above the action level of 300 and need to install measures to reduce the radon concentration - ie if your radon concentration was above 300, it's not enough to aim to make it just below 300, if your installing fans etc, you hope it's going to get much lower than that.
Read through all the website linked to by Molly. If it doesn't already say in your results/information, put the word target in the FAQs section to bring up the explanation
^The Action Level identifies radon levels above which action is most urgent but it is important that substantial reductions are made - not just aiming to get under the Action Level. The Target Level of 100 Becquerels per cubic metre aims to encourage householders to make major reductions in their radon level - to below the Target Level if possible.
Health risks below the Action Level are smaller but not zero. PHE advises householders with radon between the Target Level and the Action Level to seriously consider reducing their radon levels - especially if the household includes smokers or ex-smokers who are at greater risk from radon^
I think, when buying houses, they only recommend installing radon reduction measures (sumps, fans etc) when you're above the action level, at 109 the risk is small, so less necessary.
The main reason why radon is an issue is that there is a very very small risk for any small exposure and when you expose tens of millions of people, statistically it will effect a small number of people, but at the level you've quoted, the risk is almost immeasureably small.