The legislation was passed unanimously by the Scottish Parliament last year. It was introduced to give extra protection for children and young people from the harm caused by second-hand smoke.
Anyone caught breaking the law will be committing an offence carrying a fine of up to £1,000.
Second-hand smoke can cause serious conditions such as bronchitis, pneumonia and asthma, and children are more at risk than adults because they have smaller lungs and breathe more quickly.
Latest research highlights that the toxic particles in second hand smoke can reach harmful concentrations within a minute of lighting a cigarette in a car.
Studies have also shown the average toxic particle levels breathed in during a smoking car journey are more than 10 times higher than the average levels which can be found in the air.
A public information campaign has been running on TV and radio in the run-up to the ban, highlighting the harms of second-hand smoke and the penalties for breaking the new law.
The measure is part of the Scottish Government’s ambition to create a tobacco-free generation by 2034 – defined as a smoking rate of less than 5%. A target to reduce the proportion of children exposed to second-hand smoke in the home from 12% to 6% by 2020 has already been met.
Aileen Campbell, Minister for Public Health and Sport, said: “It’s simply not safe to smoke when a child is in the car. Dangerous levels of chemicals can build up, even on short journeys, and 85% of second-hand smoke is invisible and odourless so you can’t always see what they’re breathing in.
“We know for a fact that the poisonous chemicals in second-hand smoke are extremely damaging to our health. We also know that children breathe faster than adults, meaning they ingest more of the deadly toxins.
“This government is committed to protecting children from the harmful effects of second-hand smoke. Our target to reduce the proportion of children exposed in the home from 12 per cent to six per cent by 2020 has been met five years early. The ban on smoking in cars will help to build on that success by reinforcing the message that the toxic fumes from cigarette smoke are harmful – particularly to children.”
Irene Johnstone, Head of British Lung Foundation in Scotland said: “As 85% of second-hand smoke is invisible and odourless, many may not be aware of the dangerous levels reached, even in short car journeys. This new law will not only help reduce the exposure of second hand smoke, but will also go a long way in helping Scotland becoming a tobacco free generation.”
Sheila Duffy, Chief Executive of ASH Scotland, said: “We know from speaking to parents that they want to protect their children from tobacco smoke, but often don’t know enough about how smoke is harmful and lingers in the air even after you can’t see or smell it. This legislation sends a clear message that children should grow up in a smoke-free environment, and who could disagree with that?”