Smoking is more common in people with poor mental health than in the general population. In the UK, >40% of adults who have a serious mental illness also smoke; in the general population, the proportion of smokers is nearly 15% (Action on Smoking and Health, 2019a). Those with mental health conditions are also more likely to smoke heavily and intensively, inhaling greater volumes of carbon monoxide and other toxins (National Centre for Smoking Cessation and Training, 2018).