A new report suggests women who smoke between one and four cigarettes a day are five times more likely to develop lung cancer when compared with non-smokers.
The report by the Royal College of Physicians of Ireland (RCPI) Policy Group on Tobacco occasional smokers says they are at "a significantly higher risk" of developing cardiovascular disease, lung cancer, fertility problems and many other health problems.
One-in-five adult smokers in Ireland are occasional smokers, over 80% of those smoke once a week.
The RCPI say there is a decreased intention to quit among this group, who perceive the risks of their light smoking to be minimal.
Dr Des Cox, chair of the Policy Group on Tobacco at the RCPI, told Newstalk radio: "Those who smoke occasionally have almost a 40% greater risk of dying from smoking-related disease compared with non-smokers.
"They carry almost the same risk of cardiovascular disease as daily smokers.
"In regard to lung cancers in women ages 35-49, those who smoke between one and four cigarettes a day are five times more likely to develop lung cancer when compared to non-smokers. In men, the risk is three fold.
"Until now, anti-smoking campaigns have targeted daily smokers and while they have been successful in reducing overall smoking prevalence in Ireland, the dangers of occasional and social smoking need to be included in these campaigns going forward.
"Other lifestyle choices also need to be addressed.
"The strong link between alcohol and smoking is widely accepted and our unhealthy relationship with alcohol in Ireland is likely leading to increased smoking rates, particularly in the occasional category with 53% of the population drinking alcohol at least once a week."
Professor Mary Horgan, president of the Royal College of Physicians of Ireland, has welcomed the report.
"This report highlights the serious risks of occasional smoking.
Other recommendations include a new health promotion campaigns on the dangers of any pattern of smoking, and stricter smoking bans to be implemented in order to assist in decreasing the number of people who occasionally smoke.
It also says lifestyle risk factors - such as the association between occasional smoking and alcohol - should be highlighted.