100 people die each week in Ireland from smoking-related conditions
New laws making it a criminal offence to smoke in any car carrying children came into effect at midnight.
If caught offenders will face a fixed fine of €100.
Meanwhile, Action on Smoking in Health Ireland says 100 people die each week in Ireland as a result of smoking.
The group, which aims to reduce the impact of tobacco on Irish society, is urging smokers to visit the quit.ie website and make a plan to give up smoking.
Chairperson of ASH Ireland Dr Ross Morgan, says initial research seems to indicate that e-cigarettes are marginally healthier than tobacco, but shouldn't be seen as a long term alternative: