The link between lung cancer and to

The link between lung cancer and tobacco
smoking was first reported by Doll and Hill
(1954). They found that the risk of developing
lung cancer increases proportionally to the
amount of cigarettes smoked, with those who
smoke 25 or more cigarettes each day being
around 50 times more likely to develop lung
cancer compared with non-smokers. The Office
for National Statistics (ONS) (2006) reported
that those in routine manual occupations start
smoking at an earlier age, with 48% of men
and 40% of women smoking regularly by the
age of 16, compared with 33% of men and
28% of women in managerial and professional
occupations. Life expectancy of those in routine
manual occupations was also reduced. Passive
smoking is also a recognised risk factor for lung
cancer. The International Agency for Research
on Cancer (2013) states that there is sufficient
evidence in humans regarding the carcinogenicity
of second-hand tobacco smoke for this to be
considered a major cause of lung cancer.