[AndyTheBear]

...show me age/sex/BMI matched data before I buy it.

The article did not seem to have a link to the study, but I found it The "Study Design" section says:

This analysis aimed to verify whether mask usage was correlated with COVID-19 morbidity and mortality. Daily data on COVID-19 cases and deaths and on mask usage were obtained for all European countries. The rationale behind the choice of European countries for comparison was fourfold:

1. availability and reliability of data;
2. a relative population homogeneity and shared history of epidemics (comparing countries from different continents may bring too many confounding factors)
3. similar age stratification and access to health assistance; and
4. divergent masking policies and different percentages of mask usage among the different populations, despite the fact that the entire continent was undergoing an outburst of COVID-19 at the time period analysed in this study.

[dkGba]

I just wonder what kind of masks were worn, did everyone wear same kind of mask? did they fit and were they worn properly, did users practice good mask hygiene? Did they enter into higher risk situations because mask made them feel ‘safe’?