Almost 600 under-16s take up smoking every day in the UK, suggests research published online in Thorax.
In London alone, the daily tally is 67 - more than two classrooms-full, the calculations indicate.
National figures on smoking prevalence are available, but the researchers* wanted to estimate smoking uptake among children, to provide some baseline data to inform efforts for preventive measures, and focus attention and resources on what is "essentially a child protection issue."
This is because taking up smoking at a young age is an even greater risk to health than starting later in life, they say. Smoking at a young age affects lung development and boosts the risk of progressive lung disease (COPD).
And people who start smoking before the age of 15 run a higher risk of developing lung cancer than those who take up the habit later on, even if the cumulative number of cigarettes smoked is smaller, they add.
The researchers based their analysis on data taken from the 2011 'Smoking, drinking and drug use among young people in England' survey, which targets schoolchildren in England between the ages of 11 and 15 every year.
Questionnaires were completed by 6519 children in 219 schools. And by comparing the numbers of current smokers - regular and occasional - with smoking rates among the same age band surveyed the previous year, the researchers were able to estimate the numbers of new 11 to 15 year olds starting to smoke in 2010-11 in the UK.
To calculate the number of new child smokers for each locality, this estimate of 207,000 was then split across geographical areas according to population size and smoking prevalence among adults, on the assumption that there would be more child smokers where the proportion of adult smokers was high. Parental smoking is one of the strongest predictors of smoking among children.
The researchers then used population and adult smoking prevalence data for each of the four UK countries to calculate the number of new child smokers for each locality.
The analysis indicated that among the 3.7 million children aged between 11 and 15 in the UK, an estimated 463 start smoking every day in England, with the equivalent figures for Scotland, Wales and Northern Ireland, 55, 30, and 19, respectively.
Of 74,000 children in this age group in Birmingham, nine take up smoking every day, while the daily tally in London is 67 out of 458,000 children in this age group.
The authors acknowledge that as their figures are calculated from survey data, they can only be approximate, but the fact that they are regional might be more helpful to healthcare professionals and regulators, they say.
Smoking rates among both adults and children are falling in the UK, but the figures are still high, so the pressure needs to be kept up to reduce smoking further, say the authors.
This means increasing taxation, curbing smuggling, and running well-funded anti-smoking media campaigns, as a well as banning smoking in cars and introducing plain packaging to reduce children's exposure to branding, they say.
"Smoking is among the largest causes of preventable deaths worldwide," they write. "The present data should help to raise awareness of childhood smoking and to focus attention on the need to address this important child protection issue," they conclude.
More information: www.thorax.bmj.com/lookup/doi/… horaxjnl-2013-204379