Environmental tobacco smoke (ETS) is widely regarded as a risk factor for lung cancer and for cardiovascular disease. The position was clearly suggested in the mid 1970s, credibly asserted in the late 1980s and officially acknowledged in the late 1990s/ early 2000s. Guidance on the elimination of smoking at work has been available since the late 1980s. Smoking in indoor public places has now been banned in the UK.
At all times, the proposed association was very weak; not sufficient by itself to establish causation in an individual case. However, the degree to which risk is cumulative varies by health outcome e.g. heart disease, and, at common law, the degree of risk that is accepted as being material to an outcome has changed over the past 30 years. The emergence of modern views of material contribution may not have been predictable at the time that an exposure was relevant. Bailey v MOD sets out the current thinking on material contribution; when and how it replaces the ‘but for’ test.
We have developed an objective test of de minimis which could help the courts to assess whether any marginal exposure made a material contribution to disease.