I think you mean atherosclerotic block. Atherosclerosis means cholesterol deposition in the tubes carrying blood, leading to gradual narrowing at that site. Smoking even one cigarette /day can be extremely dangerous. Unlike alcohol, there is no safe limit for smoking. You have to eat less fast foods /fats and oils and take more fresh fruits & vegetables. The seriousness of the problem depends upon where these blocks are (heart tubes, brain tubes) and how severe these blocks are & if they are producing any symptoms like chest pain.