A child who spends just 10 minutes in the back seat of a car while someone smokes in the front, sees their daily exposure to dangerous pollutants jump by up to 30%, a new study has found.

According to US scientists, children are particularly vulnerable to the effects of passive smoking because most of this happens in their homes and cars, places that are not covered by smoking bans.

The team from California carried out 22 assessments on the air quality inside a car, after three cigarettes had been smoked over a period of 60 minutes.

For each assessment, the level of pollutants normally produced by cars and cigarettes was measured in the back seat at the breathing height of a child. This was done with both the windows open and closed.

Pollutants outside the car were also measured.

The study found that the level of pollutants inside the car was three times higher than outside, irrespective of whether the window was up or down.

Levels of PAH (polycyclic aromatic hydrocarbons) - a pollutant linked to disturbances in the immune system - were 10 times higher inside the car compared to outside.

The scientists concluded that children who spend even a short amount of time inside a car with someone who is smoking significantly increase their daily exposure to harmful pollutants.

"Children are more vulnerable than adults and their exposures to tobacco smoke in a vehicle are completely controlled by the adults with whom they share the vehicle," the scientists explained.

They noted that while smoking bans have been enacted in many public areas worldwide, in most countries, including Ireland, smoking in cars containing children is still permitted.

They added that their findings support calls for smoking bans in cars, particularly if children are present.
Earlier this year, the government confirmed that it is drafting new laws to ban smoking in cars when children are present. However, it is not yet known when this ban will come into operation or how it will be monitored.

Details of these findings are published in the journal, Tobacco Control.