Light smoking confers up to half the amount of the cardiovascular risk associated with smoking a pack of cigarettes a day

Commentary on: Hackshaw A, Morris JK, Boniface S, Tang JL, Milenkovic D. Low cigarette consumption and risk of coronary heart disease and stroke: meta-analysis of 141 cohort studies in 55 study reports. BMJ . 2018;360: j5855. Smoking is widely accepted to approximately double the risk of coronary heart disease (CHD) and stroke—but this is an average; there are currently 1.1 billion smokers worldwide, the smoking habits of whom differ in terms of quantity smoked, and in the type of cigarette smoked, duration of exposure and age of initiation.1 Therefore, it is reasonable to assume that smokers differ in terms of smoking-associated vascular risk. Although it is well recognised that there is a linear dose–response association between smoking and risk of lung cancer, the relationship with CHD and stroke has been less well defined. …