The study looked at death rates over a 28-year period
Being female or rich offers no defence against the ill heath caused by smoking, according to a new study.
Researchers from Glasgow University and NHS Scotland looked at the impact of smoking on the survival rates of 15,000 men and women over a 28-year period.
They found smokers of all social classes had a much higher risk of premature death than even the poorest non-smokers.
The survival advantage women normally have over men was also cancelled out.
The study, one of the first to examine the long-term impact of smoking on older men and women, was carried out by Dr Laurence Gruer and Dr David Gordon from NHS Health Scotland, and Professor Graham Watt and Dr Carole Hart from Glasgow University.
Their findings are being published in the British Medical Journal (BMJ) online and conclude "in essence, neither affluence nor being female offers a defence against the toxicity of tobacco".
The study revealed that a well-off professional who smokes has a much lower survival rate than a non-smoking low-paid worker of the same sex.
The researchers recruited 15,000 men and women in 1972 from Renfrew and Paisley in the west of Scotland.
The participants were grouped by gender and social class and further divided into smokers, never-smokers and ex-smokers.
Deaths rates for the groups were assessed after 14 years and 28 years.
The findings showed that, during both follow-up periods, smokers had much higher death rates than never-smokers among both women and men and in every social class.
After 28 years of follow-up, 56% of female never-smokers and 36% of male never-smokers in the lowest social classes were still alive compared with only 41% of female smokers and 24% of male smokers in the top two social class groups.
Smokers in the lowest social classes fared even worse.
The study found that quitting made a difference regardless of class
On a positive note, the study found that the death rates of ex-smokers were much closer to those of never-smokers than smokers, showing that quitting does make a difference regardless of social position.
Dr Gruer, director of public health science at NHS Health Scotland, said: "This study reinforces current policies in the United Kingdom and other countries aimed at helping smokers stop smoking.
"Accessible and effective smoking cessation advice and services, as well as strong action to discourage young people from starting to smoke, are key to reducing health inequalities. With over 23% of adults in the UK still smoking, rising to well over 40% in some places and groups, it's crucial we continue to make smoking cessation a top priority."
Commenting on the study, Health Secretary Nicola Sturgeon said: "This research reinforces the message that stopping smoking - or never taking up the habit - is the biggest single thing anyone can do to improve their health.
"We're committed to driving down smoking rates for everyone in Scotland as part of our drive to improve the nation's health.
"Measures already introduced - coupled with further moves to be introduced as part of the Health Bill - are designed to help achieve this."
She added: "As we work to reduce health inequalities, we must ensure we don't widen the inequality gap by targeting better off people who are more likely to respond to 'quit smoking' messages.
"That is why we need to target smoking prevention measures among young people in deprived communities and provide more effective support to help smokers in those communities to quit."