During which decade did the relationship between smoking and lung cancer become clearly undeniable?

The relationship between smoking and lung cancer become undeniable in the 60s

Explanation:

The relationship between lung cancer and smoking became undeniable during the 60s. During the 50s, there were studies about the relationship between cancer and cigarettes, but the rising number of cancer cases during the 60s combined with the research made during those years show the relationship between cancer and smoking.

The investigations consisted of surveys to the affected ones asking about their lifestyle, antecedents, and family history in combination with studies about the impact of the cigarette on the body and its components.

However, it took a lot of years to inform the world, which caused an epidemic of lung cancer decades later.