Is breathing other people's tobacco smoke harmful?
Second-hand tobacco smoke is a major cause of heart disease and lung cancer amongst non-smokers who work with people who smoke. It is estimated that around 700 workers a year die as a direct result of second-hand tobacco smoke in their workplace.
Second-hand smoke is also responsible for many thousands of episodes of illness and contains substances hazardous to health including tar, carbon monoxide and nicotine.
Research reported by Cancer UK estimates that non-smokers exposed to passive smoking at home or in their occupation have their risk of lung cancer raised by a quarter, while heavy exposure at work doubles the risk.
There are estimated to be around nine million adults in Britain who smoke cigarettes, although not in the workplace, where there are now strict smoking restrictions across the whole of the UK.
Five years after the smoking ban came into effect, a review of the evidence of its impact commissioned by the government in 2012 concluded that the law had produced benefits to health, and changes in attitudes and behaviour.
A study of bar workers using saliva, lung function and air quality tests showed that their respiratory health had greatly improved following the ban, due to the reduction in exposure to second-hand smoke.