> There are not many daily lifestyle choices that double your risk of dying. In a 2016 study published in the Journal of Internal Medicine, Lindqvist’s team put

> There are not many daily lifestyle choices that double your risk of dying. In a 2016 study published in the Journal of Internal Medicine, Lindqvist’s team put it in perspective: “Avoidance of sun exposure is a risk factor of a similar magnitude as smoking, in terms of life expectancy.” There's a link around "put it in perspective." Following it through to the source leads to the 2016 study, which notes: > We acknowledge several major limitations of this study. First, it is not possible to differentiate between active sun exposure habits and a healthy lifestyle, and secondly, the results are of an observational nature; therefore, a causal link cannot be proven. A further limitation is that we did not have access to exercise data from study initiation; however, similar sHR values were obtained when including exercise for those women who answered the second questionnaire in 2000. With the introduction of whole-genome scanning, a new method of getting closer to causality using observational data is Mendelian random analysis. A potential causal link between BMI and vitamin D levels has been demonstrated with this method 8. In addition, individuals with high BMI do not obtain the same increase in vitamin D levels by UV radiation as lean subjects 9. As a consequence, as BMI seems to be involved in the causal pathway of vitamin D, it should not be included as a confounder in analyses as has been performed in many studies. https://onlinelibrary.wiley.com/doi/full/10.1111/joim.12496 https://onlinelibrary.wiley.com/doi/full/10.1111/joim.12496 This adds nuance missing from the original article. Also, AFAICT, the study doesn't mention anything about sunscreen use by the women. Based on the discussion in the original article, this study looks like a smoking gun. But going a little deeper, not so much. It'd put the study into the category "needs follow-up."