We thank Dr. Fornalski and the other co-authors from the SARI organization for their interest in our study of the lung cancer risk attributed to radon in Swedish dwellings. Their message is that “…excess risk of lung cancer due to low concentrations of radon has been neither empirically detected nor theoretically demonstrated, while the opposite has in fact been supported by voluminous evidence.”

We respectfully disagree. While our paper is not an original epidemiological study on the association between lung cancer and low-level radon in Swedish dwellings, such studies have been performed [1] and show results completely compatible with the results of previous multicenter studies or meta-analyses in Europe and the USA [2–4] and large studies from China [5]. In our study we used the exposure–response (ER) function found by Darby et al. [2], since the European results were considered most representative of the Swedish situation. Importantly, there was no indication of a threshold, but the risk of lung cancer increased with a linear trend, and the estimated ER was similar for residential radon levels below 200 Bq/m3 [2].

These studies were also recently reviewed by the International Agency for Research on Cancer (IARC), and the conclusion was that the results of studies of lung cancer after residential radon exposure are compatible with the risk estimate in studies of miners with much higher exposure [6].

We also thank Dr. Fornalski and coauthors for making us aware that there exists a special organization, SARI [7], which is of the opinion that low-risk radiation is not harmful and even could be used to treat cancer and Alzheimer’s disease (!?).