UCL News


Smoking bans increase kids' exposure

18 December 2005

Total bans on smoking in public increase kids' exposure by encouraging smokers to light up at home, the first study on the direct effect of passive smoking has found.

UCL (University College London) researchers analysed exposure levels of almost 30,000 non-smokers over the last decade across the United States in states with different anti-tobacco policies to assess the effect of government intervention.

While bans in public transportation or in schools were found to decrease the exposure of non-smokers, those in recreational public places, such as bars, restaurants or recreational facilities, increased their exposure by displacing smokers to private places where they contaminate non-smokers, and in particular young children. Increasing tax on cigarettes reduces the exposure of young children but has little effect on non-smoking adults, which suggests that smokers cut down at home but not during social activities with other adults.

The results, which are published tomorrow in an Institute of Fiscal Studies Working Paper, also reveal that smoking bans increase the exposure of poorer individuals, while they decrease the exposure of richer individuals - leading to widening health disparities.

Dr Jerome Adda, of the UCL Department of Economics and lead author of the study says: "Outright bans may not be the optimal policy in tackling passive smoking. Policies aimed at reducing exposure to tobacco instead induce changes in behaviour that can offset these policies.

"Regular smokers may not reduce their habit in a uniform way: during the day, some cigarettes may be easier to cut down. If smoking is a social activity, a smoker may reduce the number of cigarettes consumed when alone, and not those consumed in company. Bans in bars may induce smokers to spend more time at home, and therefore expose other members of the household, especially children.

"Much of the current debate has focused on exposure of hospitality workers in the workplace but the voice of children, one of the most vulnerable groups to the effects of smoking, hasn't been fully considered. Our results suggest a better solution would be to provide alternative places for smoking in public, such as smoking rooms in bars."

The UCL researchers analysed data from 29,667 US citizens who took part in the National Health and Nutritional Examination Survey (NHANES) from1988 to 1994 and 1999 to 2002. Information on the age, sex, race, health, education and occupation of the individuals were collected along with data on family composition, income and geographical location. In addition, the concentration of cotinine, a metabolite of nicotine, was measured in saliva and the number of cigarettes smoked in the household.

"Cotinine is a by-product of nicotine, and is a good marker of exposure to second-hand smoke," explains Dr Adda. "The nicotine yield of a cigarette is highly correlated with the level of tar and carbon monoxide, which causes cancer and asphyxiation. Cotinine levels respond rapidly to changes in exposure, which isn't the case with other markers such as tobacco related diseases. These aren't specific to smoking and they usually take several years to develop - making it difficult to correctly identify the effects of intervention schemes."

The researchers consider four categories of passive exposure based on cotinine concentrations: 0 to 0.1 ng/ml, 0.1 to 0.2 ng/ml, 0.2 to 1.0 ng/ml and 1 to 10 ng/ml. Statistical analysis suggests that kids exposed to level above 1ng/ml are a risk of developing asthma or chest wheezing. For adults, a similar pattern is found, low exposures up to 0.2 ng/ml do not lead to higher risks of developing strokes or chronic bronchitis. But for the highest exposure group, the odds are 1.70 for strokes and 1.56 for chronic bronchitis.

Over the period of analysis levels of cotinine halved in non-smokers living with non-smokers, from approximately 0.4 ng/ml to 0.2 ng/ml. However, despite the increasing level of severity in regulations and higher excise taxes tobacco exposure of non-smokers living in smoking households did not decrease.

Analysis of exposure in children based on the types of bans imposed reveals that a total ban increases exposure by 6ng/ml in young children (4 to 8 years old) whereas a ban on public transport reduces cotinine levels by 1.5 ng/m and a ban in shopping centres by 2.5ng/ml. In the older categories of children studied (8-12 and 13-20 years old) a total ban also increased cotinine levels but by half the amount 3.2 ng/ml, which would be expected as they are more independent and would spend less time with their parents.

Investigation of state intervention based on social economic status of non-smokers reveals for the lowest income group a total ban increases exposure by 0.3ng/ml. For intermediate levels of income, taxes have a significant and negative effect, while bans appear to have no effect. For non-smokers in high income households, introduction of smoking regulations decreases (weakly) the exposure to tobacco smoke.

Dr Francesca Cornaglia, of the UCL Department of Economics, says: "These results suggest that smoking regulations have a distributional effect, increasing the exposure and putting at risk the health of poorer section of the population while it benefits individuals in higher socio-economic position. The consequence of strengthening smoking regulations would be a widening in health disparities across socio-economic groups.

"Governments in many countries are under pressure to limit passive smoking. Some pressure groups can be very vocal about these issues and suggest bold and radical reforms. As often, their point of view is laudable, but too simplistic in the sense that they do not take into account how public policies can generate perverse incentives and effects. Up to now there is little guidance on how to design optimal policies to curb passive smoking."

The study was funded by Economic and Social Research Council (ESRC)

For further information, please contact:

Dr Jerome Adda
The UCL Department of Economics
Tel: +44 (0)20 7679 5888
Email: j.adda@ucl.ac.uk

Judith H Moore
UCL Media Relations
Tel: +44 (0)20 7679 7678
Mobile: +44 (0)77 333 075 96
Email: Judith.moore@ucl.ac.uk

Notes to editors

Title: 'The Effects of Taxes and Bans on Passive Smoking'
Authors: Jerome Adda, Francesca Cornaglia
The UCL Department of Economics, University College London